6-K/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 6-K/A

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended June 30, 2013

Commission File Number 1-32591

SEASPAN CORPORATION

(Exact name of Registrant as specified in its charter)

Unit 2, 7th Floor, Bupa Centre,

141 Connaught Road West,

Hong Kong

China

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F  x            Form 40-F  ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1).    Yes  ¨    No  x

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7).    Yes  ¨    No  x

EXPLANATORY NOTE

This Amendment No. 1 to the Report on Form 6-K for the quarter ended June 30, 2013, originally filed with the Securities and Exchange Commission on August 1, 2013 (the “Form 6-K”), is being filed solely for the purposes of furnishing Interactive Data File disclosure as Exhibit 101 in accordance with Rule 405 of Regulation S-T. This Exhibit was not previously filed.

Other than as expressly set forth above, this Form 6-K/A does not, and does not purport to, amend, update or restate the information in any other item of the Form 6-K, or reflect any events that have occurred after the Form 6-K was originally filed. Pursuant to Rule 406T of Regulation S-T, the Interactive Data Files on Exhibit 101 hereto are deemed not filed or part of a registration statement or prospectus for purposes of Sections 11 or 12 of the Securities Act of 1933, as amended, are deemed not filed for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, and otherwise are not subject to liability under those sections.

Item 6. Exhibits

Exhibit Number	Description
101	The following financial information from Seaspan Corporation’s Report on Form 6-K for the quarter ended June 30, 2013, filed with the SEC on August 1, 2013, formatted in Extensible Business Reporting Language (XBRL):
	(i) Interim Consolidated Balance Sheets (Unaudited) as of June 30, 2013 and December 31, 2011;
	(ii) Interim Consolidated Statements of Operations (Unaudited) for the Three and Six Months ended June 30, 2013 and 2012;
	(iii) Interim Consolidated Statements of Comprehensive Income (Loss) (Unaudited) for the Three and Six Months ended June 30, 2013 and 2012;
	(iv) Interim Consolidated Statements of Shareholders’ Equity (Unaudited) for the Six Months ended June 30, 2013 and the Year ended December 31, 2011;
	(v) Interim Consolidated Statements of Cash Flows (Unaudited) for the Three and Six Months ended June 30, 2013 and 2012; and
	(vi) Notes to the Interim Consolidated Financial Statements (Unaudited).

This Form 6-K/A is hereby incorporated by reference into: the Registration Statement of Seaspan Corporation filed with the Securities and Exchange Commission on May 30, 2008 on Form F-3D (Registration No. 333-151329), the Registration Statement of Seaspan Corporation filed with the Securities and Exchange Commission on March 31, 2011 on Form S-8 (Registration No. 333-173207), the Registration Statement of Seaspan Corporation filed with the Securities and Exchange Commission on April 24, 2012 on Form F-3ASR (Registration No 333-180895), the Registration Statement of Seaspan Corporation filed with the Securities and Exchange Commission on June 20, 2013 on Form S-8 (Registration No. 333-189493) and the Registration Statement of Seaspan Corporation filed with the Securities and Exchange Commission on August 19, 2013 on Form F-3 ASR (Registration No 333-190718).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	SEASPAN CORPORATION
Date: October 7, 2013	By:	/S/ SAI W. CHU
		Sai W. Chu
		Chief Financial Officer

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Earnings per share

6 Months Ended

Jun. 30, 2013

Earnings Per Share [Abstract]

Earnings per share

9. Earnings per share:

The Company applies the if-converted method to determine the Earnings Per Share (“EPS”) impact for the convertible Series A preferred shares. The following is a reconciliation of the numerator and denominator used in the basic and diluted EPS computations.

Three months ended June 30, 2013	Earnings (numerator)			Shares (denominator)		Per share amount
Net earnings	$	127,154
Less:
Series A preferred share dividends		(9,423	)
Series C preferred share dividends		(8,631	)
Series D preferred share dividends		(1,545	)
Basic EPS:
Earnings attributable to common shareholders	$	107,555			64,487,000	$	1.67
Effect of dilutive securities:
Share-based compensation		—			399,000
Contingent consideration (note 2)		—			508,000
Convertible Series A preferred shares		9,423			21,309,000
Diluted EPS:
Earnings attributable to common shareholders plus assumed conversion	$	116,978			86,703,000	$	1.35

Three months ended June 30, 2012	Earnings (numerator)			Shares (denominator)		Per share amount
Net loss	$	(6,749	)
Less:
Series A preferred share dividends		(8,371	)
Series C preferred share dividends		(8,569	)
Basic and diluted EPS(1) :
Loss attributable to common shareholders	$	(23,689	)		62,608,000	$	(0.38	)

⁽¹⁾  The convertible Series A preferred shares, contingent consideration, shares held in escrow and share-based compensation are not included in the computation of diluted EPS because their effects are anti-dilutive for the period.

Six months ended June 30, 2013	Earnings (numerator)			Shares (denominator)		Per share amount
Net earnings	$	182,760
Less:
Series A preferred share dividends		(18,473	)
Series C preferred share dividends		(17,251	)
Series D preferred share dividends		(3,088	)
Basic EPS:
Earnings attributable to common shareholders	$	143,948			64,129,000	$	2.24
Effect of dilutive securities:
Share-based compensation		—			382,000
Contingent consideration (note 2)		—			743,000
Shares held in escrow (note 2)		—			95,000
Convertible Series A preferred shares		18,473			21,001,000
Diluted EPS:
Earnings attributable to common shareholders plus assumed conversion	$	162,421			86,350,000	$	1.88

Six months ended June 30, 2012	Earnings (numerator)			Shares (denominator)		Per share amount
Net earnings	$	44,509
Less:
Series A preferred share dividends		(16,499	)
Series C preferred share dividends		(17,102	)
Basic EPS:
Earnings attributable to common shareholders	$	10,908			63,153,000	$	0.17
Effect of dilutive securities:
Share-based compensation		—			204,000
Contingent consideration (note 2)		—			605,000
Shares held in escrow (note 2)		—			504,000
Diluted EPS:
Earnings attributable to common shareholders plus assumed conversion	$	10,908			64,466,000	$	0.17

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Share-based Compensation - Assumptions Used in Monte Carlo Model to Calculate Grant Date Fair Value of SARs (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average expected term	3 years 9 months 18 days
Expected volatility	39.73%
Dividend yield	4.97%
Average risk free rate	0.50%
Number of SARs	1,664,457
Tranche 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of SARs	531,885
Base price	$ 21.50
Expiration date	Dec. 31, 2015
Tranche 2 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of SARs	556,946
Base price	$ 24.00
Expiration date	Dec. 31, 2016
Tranche 3 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of SARs	575,626
Base price	$ 26.50
Expiration date	Dec. 31, 2017

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Interim Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Statement [Abstract]
Revenue	$ 167,786	$ 167,637	$ 332,710	$ 321,069
Operating expenses:
Ship operating (note 3)	37,344	31,515	74,890	66,065
Depreciation and amortization	42,840	42,284	85,593	80,215
General and administrative	11,833	6,671	19,624	12,521
Operating lease	1,097		2,183
Gain on vessel		(9,773)		(9,773)
Total operating expenses	93,114	70,697	182,290	149,028
Operating earnings	74,672	96,940	150,420	172,041
Other expenses (income):
Interest expense	15,275	19,157	30,759	36,132
Interest income	(600)	(321)	(787)	(629)
Undrawn credit facility fee	748	398	1,145	1,203
Amortization of deferred charges (note 5)	2,266	2,205	4,376	3,766
Change in fair value of financial instruments (note 14(b))	(71,193)	82,084	(68,527)	86,760
Equity loss on investment	35		69	134
Other expenses	987	166	625	166
Total Other expenses (income)	(52,482)	103,689	(32,340)	127,532
Net earnings (loss)	$ 127,154	$ (6,749)	$ 182,760	$ 44,509
Earnings (loss) per share (note 9):
Class A common share, basic	$ 1.67	$ (0.38)	$ 2.24	$ 0.17
Class A common shares, diluted	$ 1.35	$ (0.38)	$ 1.88	$ 0.17

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Acquisition of Seaspan Management Services Limited

6 Months Ended

Jun. 30, 2013

Business Combinations [Abstract]

Acquisition of Seaspan Management Services Limited

2. Acquisition of Seaspan Management Services Limited:

On January 27, 2012, the Company acquired 100 percent of Seaspan Management Services Limited (“the Manager”), an affiliated privately owned company that provided technical, administrative and strategic services to the Company. The Company’s acquisition of the Manager increased its control over access to the fixed-rate services that the Manager provides to the Company on a long-term basis, and reduced certain conflicts between the Company and its directors who have interests in the Manager.

The aggregate purchase price was $106,518,000, including:

4,220,728 of the Company’s Class A common shares	$	66,899
Contingent consideration		18,437
Settlement of intercompany balances		20,022
Stock based compensation		1,160
Aggregate purchase price	$	106,518

Under the Share Purchase Agreement, $7,500,000 or 586,212 shares of Class A common shares were deposited in escrow for settlement of potential indemnifiable damages. The escrowed shares were released on January 30, 2013, which was the end of the escrow period.

The value of the Company’s Class A common shares issued was determined based on the closing market price of those common shares on January 26, 2012.

The contingent consideration arrangement requires the Company to pay the former owners of the Manager additional consideration of 39,081 of the Company’s Class A common shares for each of certain containerships ordered or acquired by the Company, Greater China Intermodal Investments LLC (“GCI”) or Blue Water Commerce, LLC (collectively, the “Contingency Parties”) after December 12, 2011 and prior to August 15, 2014 and which are to be managed by the Company. The fair value of the contingent consideration is based on the estimated containership orders and acquisitions of each of the Contingency Parties prior to August 15, 2014. At June 30, 2013, 39,081 contingent shares are issuable.

For the six months ended June 30, 2013, the Company incurred no acquisition-related costs (June 30, 2012 - $497,000) that have been included in general and administrative expense in the Company’s consolidated statements of operations.

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Acquisition of Seaspan Management Services Limited (Tables)

6 Months Ended

Jun. 30, 2013

Business Combinations [Abstract]

Aggregate Purchase Price

The aggregate purchase price was $106,518,000, including:

4,220,728 of the Company’s Class A common shares	$	66,899
Contingent consideration		18,437
Settlement of intercompany balances		20,022
Stock based compensation		1,160
Aggregate purchase price	$	106,518

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Commitments - Schedule of Future Minimum Revenues to be Received on Committed Agreements (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Leases [Abstract]
Percentage of future minimum revenues utilization	100.00%
Remainder of 2013	$ 334,922
2014	693,794
2015	743,864
2016	706,349
2017	636,481
Thereafter	3,041,855
Future minimum revenues receivable	$ 6,157,265

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Share-based compensation

6 Months Ended

Jun. 30, 2013

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Share-based compensation

10. Share-based compensation:

A summary of the Company’s outstanding restricted shares, phantom share units and stock appreciation rights (“SARs”) as of and for the six month period ended June 30, 2013 is presented below:

Restricted shares	Number of shares			Weighted average grant date fair value
Outstanding, December 31, 2012		63,653		$	14.17
Granted		54,990			17.01
Vested		(65,578	)		14.25
Cancelled		(4,185	)		17.01
June 30, 2013		48,880		$	17.01

Phantom share units	Number of shares		Weighted average grant date fair value
Outstanding, December 31, 2012		562,000	$	13.13
Granted		95,000		19.30
June 30, 2013		657,000	$	14.02

Stock appreciation rights	Number of SARs		Weighted average grant date fair value
Outstanding, December 31, 2012		5,674,148	$	2.03
Granted		1,664,457		3.51
June 30, 2013		7,338,605	$	2.37

As vested outstanding phantom share units are only exchanged for common shares upon written notice from the holder, the phantom share units that are exchanged for common shares may include units that vested in prior periods. At June 30, 2013, 460,000 (December 31, 2012 - 328,000) of the outstanding phantom share units were vested and available for exchange by the holder. At June 30, 2013, there are 738,514 (December 31, 2012 - 884,319) remaining shares left for issuance under this Plan.

On March 27, 2013, the Company granted 1,664,457 SARs to certain members of management (the “Participants”) which vest and become exercisable in three tranches when and if the fair market value of the common shares equals or exceeds the applicable base price for each tranche for any 20 consecutive trading days on or before the expiration date of each tranche. The Participants may exercise each vested tranche of SARs and receive common shares with a value equal to the difference between the applicable base price and the fair market value of the common shares on the exercise date. The common shares received on the exercise of SARs are subject to a retention requirement where the Participant is required to retain ownership of 50% of the net after tax number of shares until the later of March 22, 2018 or 120 days after the exercise date.

The assumptions used in the Monte Carlo model to calculate the grant date fair value of the SARs were as follows:

Average expected term	3.8 years
Expected volatility	39.73%
Dividend yield	4.97%
Average risk free rate	0.50%

	Number of SARs		Base price		Expiration date
Tranche 1		531,885	$	21.50		December 31, 2015
Tranche 2		556,946		24.00		December 31, 2016
Tranche 3		575,626		26.50		December 31, 2017
Total		1,664,457

During the three and six months ended June 30, 2013, the Company recognized $701,000 and $1,300,000 (June 30, 2012 - $656,000 and $1,404,000) related to restricted share units and phantom share units and $150,000 and $300,000 (June 30, 2012 - $188,000 and $375,000) in share-based compensation expenses related to other stock-based awards.

During the three and six months ended June 30, 2013, the first tranche of SARs vested earlier than what had been estimated using the Monte Carlo model. As a result, recognition of $2,550,000 in share-based compensation expense related to the first tranche of SARs was accelerated during the three and six months ended June 30, 2013 (June 30, 2012 – nil and nil). The total share-based compensation expense related to SARs, including the accelerated expense of $2,550,000 described above, for the three and six months ended June 30, 2013 was $5,780,000 and $7,842,000 (June 30, 2012 – nil and nil).

In addition, during the three and six months ended June 30, 2013, the Company recognized $382,000 and $756,000 (June 30, 2012 - nil and $184,000) in other stock-based awards that were capitalized to vessels under construction.

During the three and six months ended June 30, 2013, the total fair value of shares vested was $33,000 and $935,000 (June 30, 2012 - nil and $563,000) and the total fair value of shares cancelled was $71,000 (June 30, 2012 - nil and nil).

At June 30, 2013, there was $11,336,000 (December 31, 2012 - $12,519,000) of total unrecognized compensation costs relating to unvested share-based compensation awards and SARs, which are expected to be recognized over a weighted average period of 20 months.

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Long-term debt - Additional Information (Detail) (USD $)	1 Months Ended
	Feb. 28, 2013 10000 TEU vessels [Member] Vessel	Apr. 25, 2013 Vessel class 14000 TEU [Member] Vessel	Jun. 30, 2013 Vessel class 4600 TEU [Member] Vessel	Feb. 28, 2013 Term loan credit facilities [Member] Non interest bearing until relevant vessel delivered [Member] Loans	Apr. 25, 2013 Term loan credit facilities [Member] Asian bank [Member]	Jan. 28, 2013 Term loan credit facilities [Member] Asian bank [Member]	Apr. 25, 2013 Term loan credit facilities [Member] Asian bank [Member] Vessel class 14000 TEU [Member] Vessel	Jun. 30, 2013 Term loan credit facilities [Member] U.S bank and Australian bank [Member]	Feb. 28, 2013 Term loan one [Member] Non interest bearing until relevant vessel delivered [Member]	Feb. 28, 2013 Term loan two [Member] Non interest bearing until relevant vessel delivered [Member]
Debt Instrument [Line Items]
Term loan facility with bank					$ 174,000,000	$ 340,000,000		$ 30,000,000
Commitment fee on undrawn amount					0.75%	0.40%
Number of term loans				2
Term loans									$ 4,500,000	$ 4,500,000
Number of vessels	2	2	2
Capacity of vessel class	10,000	14,000	4,600
Expected delivery dates of vessels				2014
Interest rate on debt instrument				6.00%
Increase in Interest rate on debt instrument				7.00%
Debt instrument payment extending number years				Two years
Number of vessels to be constructed							2
Number of vessels acquired			2

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Commitments - Schedule of Commitment Under Operating Leases (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Leases [Abstract]
Remainder of 2013	$ 3,403
2014	6,882
2015	6,893
2016	6,911
2017	6,969
Thereafter	24,088
Operating leases, future minimum payments due	$ 55,146

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Acquisition of Seaspan Management Services Limited - Aggregate Purchase Price (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Business Combinations [Abstract]
4,220,728 of the Company's Class A common shares	$ 66,899
Contingent consideration	18,437
Settlement of intercompany balances	20,022
Stock based compensation	1,160
Aggregate purchase price	$ 106,518

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Deferred charges (Tables)

6 Months Ended

Jun. 30, 2013

Text Block [Abstract]

Deferred Charges

	Dry-docking			Financing fees			Total
December 31, 2012	$	12,694		$	31,122		$	43,816
Cost incurred		1,193			16,355			17,548
Amortization expensed		(1,806	)		(4,376	)		(6,182	)
Amortization capitalized		—			(477	)		(477	)
June 30, 2013	$	12,081		$	42,624		$	54,705

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Vessels (Tables)

6 Months Ended

Jun. 30, 2013

Property Plant And Equipment [Abstract]

Schedule of Vessels

June 30, 2013	Cost		Accumulated depreciation		Net book value
Vessels	$	5,365,016	$	636,752	$	4,728,264
Vessels under construction		174,650		—		174,650
Vessels	$	5,539,666	$	636,752	$	4,902,914

December 31, 2012	Cost		Accumulated depreciation		Net book value
Vessels	$	5,339,550	$	553,582	$	4,785,968
Vessels under construction		77,305		—		77,305
Vessels	$	5,416,855	$	553,582	$	4,863,273

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Deferred revenue - Deferred Revenue (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Deferred Revenue Disclosure [Abstract]
Deferred revenue on time charters	$ 6,210	$ 19,861
Deferred interest on lease receivable	10,123	12,503
Other deferred revenue	1,040	650
Deferred revenue	17,373	33,014
Current portion	(11,481)	(25,111)
Deferred revenue	$ 5,892	$ 7,903

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Commitments (Tables)

6 Months Ended

Jun. 30, 2013

Commitments And Contingencies Disclosure [Abstract]

Schedule of Outstanding Commitments for Purchase of Additional Vessels and Installment Payments for Vessels

(a) As of June 30, 2013, based on the contractual delivery dates, the outstanding commitments for the purchase of additional vessels and installment payments for vessels under construction is as follows:

Remainder of 2013	$	44,380
2014		418,640
2015		235,380
	$	698,400

Schedule of Future Minimum Revenues to be Received on Committed Agreements

(b) As of June 30, 2013, the minimum future revenues to be received on committed time charter party agreements and interest income from sales-type capital leases are approximately:

Remainder of 2013	$	334,922
2014		693,794
2015		743,864
2016		706,349
2017		636,481
Thereafter		3,041,855
	$	6,157,265

The minimum future revenues are based on 100% utilization, relate to committed time charter party agreements in effect at June 30, 2013 and assume no renewals or extensions.

Schedule of Commitment Under Operating Leases

(c) As of June 30, 2013, the commitment under operating leases is as follows:

Remainder of 2013	$	3,403
2014		6,882
2015		6,893
2016		6,911
2017		6,969
Thereafter		24,088
	$	55,146

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Related party transactions - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Related Party Transactions [Abstract]
Administrative and strategic services	$ 72,000
Amounts due from related parties	1,567,000	1,501,000
Amounts due to other related parties	$ 596,000

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Share capital - Schedule of Preferred Shares Outstanding (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Class of Stock [Line Items]
Shares Authorized	65,000,000	65,000,000
Shares Issued	17,305,000	17,305,000
Series A preferred shares [Member]
Class of Stock [Line Items]
Shares Authorized	315,000
Shares Issued	200,000
Liquidation preference	$ 324,345	$ 305,872
Series B Preferred Shares [Member]
Class of Stock [Line Items]
Shares Authorized	260,000
Shares Issued
Liquidation preference
Series C preferred shares [Member]
Class of Stock [Line Items]
Shares Authorized	40,000,000
Shares Issued	14,000,000
Liquidation preference	350,000	350,000
Series D preferred shares [Member]
Class of Stock [Line Items]
Shares Authorized	20,000,000
Shares Issued	3,105,000
Liquidation preference	77,625	77,625
Series R preferred stock [Member]
Class of Stock [Line Items]
Shares Authorized	1,000,000
Shares Issued
Liquidation preference

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Earnings per share (Tables)

6 Months Ended

Jun. 30, 2013

Earnings Per Share [Abstract]

Schedule of Reconciliation of Numerator and Denominator Used in Basic and Diluted EPS Computations

The following is a reconciliation of the numerator and denominator used in the basic and diluted EPS computations.

Three months ended June 30, 2013	Earnings (numerator)			Shares (denominator)		Per share amount
Net earnings	$	127,154
Less:
Series A preferred share dividends		(9,423	)
Series C preferred share dividends		(8,631	)
Series D preferred share dividends		(1,545	)
Basic EPS:
Earnings attributable to common shareholders	$	107,555			64,487,000	$	1.67
Effect of dilutive securities:
Share-based compensation		—			399,000
Contingent consideration (note 2)		—			508,000
Convertible Series A preferred shares		9,423			21,309,000
Diluted EPS:
Earnings attributable to common shareholders plus assumed conversion	$	116,978			86,703,000	$	1.35

Three months ended June 30, 2012	Earnings (numerator)			Shares (denominator)		Per share amount
Net loss	$	(6,749	)
Less:
Series A preferred share dividends		(8,371	)
Series C preferred share dividends		(8,569	)
Basic and diluted EPS(1) :
Loss attributable to common shareholders	$	(23,689	)		62,608,000	$	(0.38	)

⁽¹⁾  The convertible Series A preferred shares, contingent consideration, shares held in escrow and share-based compensation are not included in the computation of diluted EPS because their effects are anti-dilutive for the period.

Six months ended June 30, 2013	Earnings (numerator)			Shares (denominator)		Per share amount
Net earnings	$	182,760
Less:
Series A preferred share dividends		(18,473	)
Series C preferred share dividends		(17,251	)
Series D preferred share dividends		(3,088	)
Basic EPS:
Earnings attributable to common shareholders	$	143,948			64,129,000	$	2.24
Effect of dilutive securities:
Share-based compensation		—			382,000
Contingent consideration (note 2)		—			743,000
Shares held in escrow (note 2)		—			95,000
Convertible Series A preferred shares		18,473			21,001,000
Diluted EPS:
Earnings attributable to common shareholders plus assumed conversion	$	162,421			86,350,000	$	1.88

Six months ended June 30, 2012	Earnings (numerator)			Shares (denominator)		Per share amount
Net earnings	$	44,509
Less:
Series A preferred share dividends		(16,499	)
Series C preferred share dividends		(17,102	)
Basic EPS:
Earnings attributable to common shareholders	$	10,908			63,153,000	$	0.17
Effect of dilutive securities:
Share-based compensation		—			204,000
Contingent consideration (note 2)		—			605,000
Shares held in escrow (note 2)		—			504,000
Diluted EPS:
Earnings attributable to common shareholders plus assumed conversion	$	10,908			64,466,000	$	0.17

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Subsequent events - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended			1 Months Ended		3 Months Ended		6 Months Ended		1 Months Ended	3 Months Ended	6 Months Ended	1 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jul. 31, 2013 Subsequent events [Member]	Jul. 19, 2013 Subsequent events [Member]	Jul. 31, 2013 Subsequent events [Member] Vessel class 14000 TEU [Member] Vessel	Jul. 31, 2013 Subsequent events [Member] 4600 TEU [Member] Vessel	Jun. 30, 2013 Series C preferred shares [Member]	Jun. 30, 2012 Series C preferred shares [Member]	Jun. 30, 2013 Series C preferred shares [Member]	Jun. 30, 2012 Series C preferred shares [Member]	Jul. 31, 2013 Series C preferred shares [Member] Subsequent events [Member]	Jun. 30, 2013 Series D preferred shares [Member]	Jun. 30, 2013 Series D preferred shares [Member]	Jul. 31, 2013 Series D preferred shares [Member] Subsequent events [Member]	Jul. 31, 2013 Series C and Series D preferred share [Member] Subsequent events [Member]	Jul. 31, 2013 Common shares [Member] Subsequent events [Member]
Capacity of vessel class					14,000	4,600
Fixed-rate time charter period						2 years
Dividends on preferred shares, per share											$ 0.59375			$ 0.496875
Dividends, preferred stock	$ 18,976,000	$ 33,250,000					$ 8,631,000	$ 8,569,000	$ 17,251,000	$ 17,102,000		$ 1,545,000	$ 3,088,000		$ 9,855,000
Dividends declared date											Jul. 16, 2013			Jul. 16, 2013		Jul. 24, 2013
Dividends date paid											Jul. 30, 2013			Jul. 30, 2013		Aug. 21, 2013
Dividends date of record											Jul. 29, 2013			Jul. 29, 2013		Aug. 12, 2013
Aggregate purchase price				550,000,000
Dividends on common shares, per share																$ 0.3125
Term loan facility			$ 83,000,000
Number of vessels					1

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Vessels - Schedule of Vessels (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Cost	$ 5,539,666	$ 5,416,855
Accumulated depreciation	636,752	553,582
Net book value	4,902,914	4,863,273
Vessels [Member]
Property, Plant and Equipment [Line Items]
Cost	5,365,016	5,339,550
Accumulated depreciation	636,752	553,582
Net book value	4,728,264	4,785,968
Vessels under construction [Member]
Property, Plant and Equipment [Line Items]
Cost	174,650	77,305
Accumulated depreciation
Net book value	$ 174,650	$ 77,305

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Related party transactions (Tables)

6 Months Ended

Jun. 30, 2013

Related Party Transactions [Abstract]

Schedule of Costs Incurred under Management Agreements

The Company incurred the following costs under the management agreements with the Manager which were incurred prior to the date of acquisition:

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
Technical services	$	—	$	—	$	—	$	9,700
Dry-dock activities included in technical services		—		—		—		421
Other services		—		—		—		410

Schedule of Costs Incurred with Related Parties

The Company incurred the following costs with related parties:

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
Arrangement fees	$	1,512	$	—	$	4,564	$	—
Transaction fees		653		—		1,513		—
Reimbursed expenses		18		—		36		—

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Interim Consolidated Statements of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total USD ($)	Series C preferred shares [Member] USD ($)	Class A common shares [Member]	Class C common shares [Member]	Series A preferred shares [Member]	Series C preferred shares [Member]	Series D preferred shares [Member]	Common shares [Member] USD ($)	Preferred shares [Member] USD ($)	Treasury shares USD ($)	Additional paid-in capital [Member] USD ($)	Additional paid-in capital [Member] Series C preferred shares [Member] USD ($)	Deficit [Member] USD ($)	Deficit [Member] Series C preferred shares [Member] USD ($)	Accumulated other comprehensive loss [Member] USD ($)
Balance at Dec. 31, 2011	$ 1,183,425
Balance, shares at Dec. 31, 2011					200,000	14,000,000
Shares issued through dividend reinvestment program	5,277
Share-based compensation expense (note 10):
Net earnings	44,509
Dividends on preferred shares		(17,102)
Balance at Jun. 30, 2012
Balance at Dec. 31, 2011	1,183,425							696	142		1,860,979		(622,406)		(55,986)
Balance, shares at Dec. 31, 2011			69,620,060	100	200,000	14,000,000
Preferred shares issued	77,625								31		77,594
Preferred shares issued, shares							3,105,000
Fees and expenses in connection with issuance of preferred shares	(2,929)										(2,929)
Shares issued through dividend reinvestment program	7,168							5			7,163
Shares issued through dividend reinvestment program, shares			474,249
Share-based compensation expense (note 10):
Restricted class A common shares, phantom share units and stock appreciation rights issued/granted	4,028							3			4,025
Restricted class A common shares, phantom share units and stock appreciation rights issued/granted, shares			123,878
Other share-based compensation	839										839
Other share-based compensation, shares			70,836
Net earnings	121,305												121,305
Other comprehensive income	9,146														9,146
Dividends on class A common shares	(58,940)												(58,940)
Shares repurchased, including related expenses	(172,812)							(114)			(172,698)
Shares repurchased, including related expenses, shares			(11,448,101)
Shares issued and retired on acquisition (note 2)	83,275							42			83,233
Shares issued and retired on acquisition (note 2), shares			4,220,728	(100)
Treasury shares, value	(313)							(1)		(312)
Treasury shares			(19,433)
Dividends on preferred shares	(33,250)												(33,250)
Amortization of Series C issuance costs												862		(862)
Balance at Dec. 31, 2012	1,218,567							631	173	(312)	1,859,068		(594,153)		(46,840)
Balance, shares at Dec. 31, 2012			63,042,217		200,000	14,000,000	3,105,000
Fees and expenses in connection with issuance of preferred shares	(55)										(55)
Shares issued through dividend reinvestment program	15,348							8			15,340
Shares issued through dividend reinvestment program, shares			751,215
Share-based compensation expense (note 10):
Restricted class A common shares, phantom share units and stock appreciation rights issued/granted	9,143							1			9,142
Restricted class A common shares, phantom share units and stock appreciation rights issued/granted, shares			50,805
Fleet growth payments (note 2)								3			(3)
Fleet growth payments (note 2), shares			351,729
Other share-based compensation	3,727							1			3,726
Other share-based compensation, shares			159,020
Net earnings	182,760												182,760
Other comprehensive income	3,405														3,405
Dividends on class A common shares	(35,786)												(35,786)
Treasury shares, value	(120)									(120)
Dividends on preferred shares	(18,976)	(17,251)											(18,976)
Amortization of Series C issuance costs												628		(628)
Balance at Jun. 30, 2013	1,378,013							644	173	(432)	1,887,846		(466,783)		(43,435)
Balance, shares at Jun. 30, 2013			64,354,986		200,000	14,000,000	3,105,000
Balance at Mar. 31, 2013
Shares issued through dividend reinvestment program	8,726
Share-based compensation expense (note 10):
Net earnings	127,154
Dividends on preferred shares		(8,631)
Balance at Jun. 30, 2013	$ 1,378,013								$ 173
Balance, shares at Jun. 30, 2013					200,000	14,000,000	3,105,000

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Interim Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Operating activities:
Net earnings (loss)	$ 127,154	$ (6,749)	$ 182,760	$ 44,509
Items not involving cash:
Depreciation and amortization	42,840	42,284	85,593	80,215
Share-based compensation (note 10)	6,630	1,943	9,441	2,529
Amortization of deferred charges (note 5)	2,266	2,205	4,376	3,766
Amounts reclassified from other comprehensive loss to interest expense	1,384	2,194	2,963	4,736
Unrealized change in fair value of financial instruments	(102,988)	51,354	(131,857)	25,571
Gain on vessel		(9,773)		(9,773)
Equity loss on investment	35		69	134
Changes in assets and liabilities:
Accounts receivable and prepaid expenses	23,385	6,897	(899)	25,387
Other assets and deferred charges	(951)	(6,344)	(953)	(8,586)
Accounts payable and accrued liabilities	3,170	10,180	497	(19,437)
Deferred revenue	(1,324)	(682)	(15,641)	(1,477)
Other long-term liabilities	(40)	(1,314)	(505)	(5,620)
Cash from operating activities	101,561	92,195	135,844	141,954
Financing activities:
Draws on credit facilities (note 7)		69,997	9,000	115,487
Repayment of credit facilities (note 7)	(12,219)	(2,760)	(33,226)	(12,802)
Shares repurchased, including related expenses		(329)		(170,938)
Other long-term liabilities	(9,787)	(8,335)	(19,860)	(32,984)
Financing fees (note 5)	(2,903)	198	(14,780)	182
Dividends on common shares	(11,266)	(14,811)	(20,438)	(22,178)
Dividends on preferred shares	(9,857)	(8,312)	(18,976)	(16,625)
Cash from (used in) financing activities	(46,032)	35,648	(98,280)	(139,858)
Investing activities:
Expenditures for vessels	(33,065)	(77,640)	(92,294)	(164,275)
Short term investments	(15,323)	141	(45,596)	(10,073)
Cash acquired on acquisition of Seaspan Management Services Ltd. (note 2)				23,910
Restricted cash (note 1)	(500)	2,100	(1,900)	(3,900)
Other assets	(24,595)	(6,511)	(23,477)	530
Investment in affiliate			(1,111)
Cash used in investing activities	(73,483)	(81,910)	(164,378)	(153,808)
Increase (decrease) in cash and cash equivalents	(17,954)	45,933	(126,814)	(151,712)
Cash and cash equivalents, beginning of period	272,518	283,478	381,378	481,123
Cash and cash equivalents, end of period	254,564	329,411	254,564	329,411
Supplementary cash flow information (note 11)

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Related party transactions

6 Months Ended

Jun. 30, 2013

Related Party Transactions [Abstract]

Related party transactions

3. Related party transactions:

Prior to the acquisition of the Manager on January 27, 2012, the ultimate beneficial owners of the Manager directly and indirectly owned common shares and preferred shares, of the Company. The Company had entered into management agreements with the Manager for the provision of certain technical, strategic and administrative services for fees:

• Technical Services - The Manager was responsible for providing ship operating services to the Company in exchange for a fixed fee per day per vessel. The technical services fee did not include certain extraordinary items, as defined in the management agreements.

• Administrative and Strategic Services - The Manager provided administrative and strategic services to the Company for the management of the business for a fixed fee of $72,000 per year. The Company also reimbursed all reasonable expenses incurred by the Manager in providing these services to the Company.

The Company incurred the following costs under the management agreements with the Manager which were incurred prior to the date of acquisition:

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
Technical services	$	—	$	—	$	—	$	9,700
Dry-dock activities included in technical services		—		—		—		421
Other services		—		—		—		410

The Company incurred the following costs with related parties:

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
Arrangement fees	$	1,512	$	—	$	4,564	$	—
Transaction fees		653		—		1,513		—
Reimbursed expenses		18		—		36		—

At June 30, 2013, the Company had $1,567,000 (December 31, 2012 - $1,501,000) due from other related parties included in accounts receivable and $596,000 (December 31, 2012 - nil) included in accounts payable.

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Basis of Presentation

6 Months Ended

Jun. 30, 2013

Accounting Policies [Abstract]

Basis of Presentation

1. Basis of Presentation:

The accompanying interim financial information of Seaspan Corporation (“the Company”) have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”), on a basis consistent with those followed in the December 31, 2012 audited annual consolidated financial statements. The accompanying interim financial information is unaudited and reflects all adjustments, consisting of normal recurring adjustments, which, in the opinion of management, are necessary for a fair presentation of results for the interim periods presented. These unaudited interim consolidated financial statements do not include all the disclosures required under U.S. GAAP for annual financial statements and should be read in conjunction with the December 31, 2012 consolidated financial statements filed with the Securities and Exchange Commission in the Company’s 2012 Annual Report on Form 20-F.

Certain comparative information has been reclassified to conform with the financial statement presentation adopted for the current year.

The Company has recast the 2012 consolidated balance sheet and statements of cash flows for the three and six months ended June 30, 2012 to separately present balances of and movements in restricted cash, included in other assets, from cash and cash equivalents. This reclassification, which is immaterial, had no impact on the comparative consolidated statements of operations.

The Company has adopted Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2013-02, Comprehensive Income (Topic 220): Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income (“ASU 2013-02”). ASU 2013-02 amended existing guidance by requiring additional disclosure either on the face of the income statement or in the notes to the financial statements of significant amounts reclassified out of accumulated other comprehensive income. ASU 2013-01 requires prospective adoption, and affects financial statement disclosure only. The adoption of ASU 2013-01 had no effect on the results of operations or financial position of the Company.

The Company adopted FASB ASU No. 2013-01, Balance Sheet (Topic 210): Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities (“ASU 2013-01”). ASU 2013-01 amended existing guidance by requiring additional disclosure about financial instruments and derivative instruments that are either (1) offset in the statement of financial position or (2) subject to an enforceable master netting arrangement. ASU 2013-01 requires retrospective disclosure for all comparative periods. The adoption of ASU 2013-01 did not have a material impact on the financial position of the Company.

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Related party transactions - Schedule of Costs Incurred under Management Agreements (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Technical services [Member]
Related Party Transaction [Line Items]
Costs incurred under the management agreements				$ 9,700
Dry-dock activities included in technical services [Member]
Related Party Transaction [Line Items]
Costs incurred under the management agreements				421
Other services [Member]
Related Party Transaction [Line Items]
Costs incurred under the management agreements				$ 410

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Deferred revenue (Tables)

6 Months Ended

Jun. 30, 2013

Deferred Revenue [Abstract]

Deferred Revenue

	June 30, 2013			December 31, 2012
Deferred revenue on time charters	$	6,210		$	19,861
Deferred interest on lease receivable		10,123			12,503
Other deferred revenue		1,040			650
Deferred revenue		17,373			33,014
Current portion		(11,481	)		(25,111	)
Deferred revenue	$	5,892		$	7,903

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Share-based compensation (Tables)

6 Months Ended

Jun. 30, 2013

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Outstanding Restricted Shares, Phantom Share Units and Stock Appreciation Rights

A summary of the Company’s outstanding restricted shares, phantom share units and stock appreciation rights (“SARs”) as of and for the six month period ended June 30, 2013 is presented below:

Restricted shares	Number of shares			Weighted average grant date fair value
Outstanding, December 31, 2012		63,653		$	14.17
Granted		54,990			17.01
Vested		(65,578	)		14.25
Cancelled		(4,185	)		17.01
June 30, 2013		48,880		$	17.01

Phantom share units	Number of shares		Weighted average grant date fair value
Outstanding, December 31, 2012		562,000	$	13.13
Granted		95,000		19.30
June 30, 2013		657,000	$	14.02

Stock appreciation rights	Number of SARs		Weighted average grant date fair value
Outstanding, December 31, 2012		5,674,148	$	2.03
Granted		1,664,457		3.51
June 30, 2013		7,338,605	$	2.37

Assumptions Used in Monte Carlo Model to Calculate Grant Date Fair Value of SARs

The assumptions used in the Monte Carlo model to calculate the grant date fair value of the SARs were as follows:

Average expected term	3.8 years
Expected volatility	39.73%
Dividend yield	4.97%
Average risk free rate	0.50%

	Number of SARs		Base price		Expiration date
Tranche 1		531,885	$	21.50		December 31, 2015
Tranche 2		556,946		24.00		December 31, 2016
Tranche 3		575,626		26.50		December 31, 2017
Total		1,664,457

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Acquisition of Seaspan Management Services Limited - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jan. 27, 2012
Business Acquisition [Line Items]
Business acquisition percentage of voting interests acquired			100.00%
Amount deposited in escrow	$ 7,500,000
Contingent shares issuable	39,081
Acquisition-related costs		$ 497,000
Class A common shares [Member]
Business Acquisition [Line Items]
Shares deposited in escrow	586,212
Additional contingent consideration	39,081

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Commitments - Schedule of Outstanding Commitments for Purchase of Additional Vessels and Installment Payments for Vessels (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Commitments And Contingencies Disclosure [Abstract]
Remainder of 2013	$ 44,380
2014	418,640
2015	235,380
Purchase obligations for additional vessels	$ 698,400

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Earnings per share - Schedule of Reconciliation of Numerator and Denominator Used in Basic and Diluted EPS Computations (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Earnings attributable to common shareholders plus assumed conversion, value	$ 116,978		$ 162,421	$ 10,908
Earnings attributable to common shareholders, value	107,555	(23,689)	143,948	10,908
Net earnings (loss)	127,154	(6,749)	182,760	44,509	121,305
Preferred stock dividends			(18,976)		(33,250)
Earnings attributable to common shareholders, shares	64,487,000		64,129,000	63,153,000
Share-based compensation, shares	399,000		382,000	204,000
Contingent consideration, shares	508,000		743,000	605,000
Shares held in escrow, shares			95,000	504,000
Earnings attributable to common shareholders plus assumed conversion, shares	86,703,000	62,608,000	86,350,000	64,466,000
Earnings attributable to common shareholders, per share	$ 1.67	$ (0.38)	$ 2.24	$ 0.17
Earnings attributable to common shareholders plus assumed conversion, per share	$ 1.35	$ (0.38)	$ 1.88	$ 0.17
Series A preferred shares [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Preferred stock dividends	(9,423)	(8,371)	(18,473)	(16,499)
Convertible Series A preferred shares, value	9,423		18,473
Convertible Series A preferred shares, shares	21,309,000		21,001,000
Series C preferred shares [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Preferred stock dividends	(8,631)	(8,569)	(17,251)	(17,102)
Series D preferred shares [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Preferred stock dividends	$ (1,545)		$ (3,088)

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Deferred charges - Deferred Charges (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Beginning Balance, Dry-docking	$ 12,694
Cost incurred, Dry-docking	1,193
Amortization expensed, Dry-docking	(1,806)
Amortization capitalized, Dry-docking
Ending Balance, Dry-docking	12,081
Beginning Balance, Financing fees	31,122
Cost incurred, Financing fees	16,355
Amortization expensed, Financing fees	(4,376)
Amortization capitalized, Financing fees	(477)
Ending Balance, Financing fees	42,624
Beginning Balance, Total	43,816
Cost incurred, Total	17,548
Amortization expensed, Total	(6,182)
Amortization capitalized, Total	(477)
Ending Balance, Total	$ 54,705

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Interim Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, authorized	65,000,000	65,000,000
Preferred shares, issued	17,305,000	17,305,000
Preferred shares, outstanding	17,305,000	17,305,000
Class A common shares [Member]
Common shares, par value	$ 0.01	$ 0.01
Common shares, authorized	200,000,000	200,000,000
Common shares, issued	64,354,986	63,042,217
Common shares, outstanding	64,354,986	63,042,217
Class B common shares [Member]
Common shares, par value	$ 0.01	$ 0.01
Common shares, authorized	25,000,000	25,000,000
Common shares, issued
Common shares, outstanding
Class C common shares [Member]
Common shares, par value	$ 0.01	$ 0.01
Common shares, authorized	100	100
Common shares, issued
Common shares, outstanding

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Deferred revenue

6 Months Ended

Jun. 30, 2013

Deferred Revenue [Abstract]

Deferred revenue

6. Deferred revenue:

	June 30, 2013			December 31, 2012
Deferred revenue on time charters	$	6,210		$	19,861
Deferred interest on lease receivable		10,123			12,503
Other deferred revenue		1,040			650
Deferred revenue		17,373			33,014
Current portion		(11,481	)		(25,111	)
Deferred revenue	$	5,892		$	7,903

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Interim Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net earnings (loss)	$ 127,154	$ (6,749)	$ 182,760	$ 44,509
Other comprehensive income:
Amounts reclassified to earnings (loss) during the period relating to cash flow hedging instruments	1,603	2,412	3,405	5,120
Comprehensive income (loss)	$ 128,757	$ (4,337)	$ 186,165	$ 49,629

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Concentrations - Schedule of Revenue Derived from Customers (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenue, Major Customer [Line Items]
Revenue	$ 167,786	$ 167,637	$ 332,710	$ 321,069
COSCON [Member]
Revenue, Major Customer [Line Items]
Revenue	74,671	72,584	149,268	129,786
CSCL Asia [Member]
Revenue, Major Customer [Line Items]
Revenue	34,645	38,877	69,242	78,678
K-Line [Member]
Revenue, Major Customer [Line Items]
Revenue	18,984	18,983	37,762	37,969
HL USA [Member]
Revenue, Major Customer [Line Items]
Revenue	14,739	14,697	29,319	29,176
Other [Member]
Revenue, Major Customer [Line Items]
Revenue	$ 24,747	$ 22,496	$ 47,119	$ 45,460

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Interim Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 254,564	$ 381,378
Short-term investments	81,696	36,100
Accounts receivable	11,470	9,573
Prepaid expenses	27,144	20,902
Gross investment in lease	19,235	15,977
Total current assets	394,109	463,930
Vessels (note 4)	4,902,914	4,863,273
Deferred charges (note 5)	54,705	43,816
Gross investment in lease	69,323	79,821
Goodwill	75,321	75,321
Other assets	109,541	83,661
Fair value of financial instruments (note 14(b))	52,143	41,031
Total assets	5,658,056	5,650,853
Current liabilities:
Accounts payable and accrued liabilities	51,586	49,997
Current portion of deferred revenue (note 6)	11,481	25,111
Current portion of long-term debt (note 7)	150,612	66,656
Current portion of other long-term liabilities	38,927	38,542
Total current liabilities	252,606	180,306
Deferred revenue (note 6)	5,892	7,903
Long-term debt (note 7)	2,942,746	3,024,288
Other long-term liabilities	592,804	613,049
Fair value of financial instruments (note 14(b))	485,995	606,740
Share capital (note 8):
Common and Preferred Shares	817	804
Treasury shares	(432)	(312)
Additional paid in capital	1,887,846	1,859,068
Deficit	(466,783)	(594,153)
Accumulated other comprehensive loss	(43,435)	(46,840)
Total Shareholders' equity	1,378,013	1,218,567
Total liabilities and shareholders' equity	5,658,056	5,650,853
Commitments (note 12)
Subsequent events (note 15)

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Share-based compensation - Summary of Outstanding Restricted Shares, Phantom Share Units and Stock Appreciation Rights (Detail) (USD $)	1 Months Ended	6 Months Ended
	Mar. 27, 2013	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		1,664,457
Restricted shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of shares		63,653
Granted		54,990
Vested		(65,578)
Cancelled		(4,185)
Ending balance, Number of shares		48,880
Beginning balance, Weighted average grant date fair value		$ 14.17
Granted		$ 17.01
Vested		$ 14.25
Cancelled		$ 17.01
Ending balance, Weighted average grant date fair value		$ 17.01
Phantom share units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of shares		562,000
Granted		95,000
Ending balance, Number of shares		657,000
Beginning balance, Weighted average grant date fair value		$ 13.13
Granted		$ 19.30
Ending balance, Weighted average grant date fair value		$ 14.02
Stock appreciation rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of shares		5,674,148
Granted	1,664,457	1,664,457
Ending balance, Number of shares		7,338,605
Beginning balance, Weighted average grant date fair value		$ 2.03
Granted		$ 3.51
Ending balance, Weighted average grant date fair value		$ 2.37

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Long-term debt (Tables)

6 Months Ended

Jun. 30, 2013

Debt Disclosure [Abstract]

Schedule of Long-Term Debt

	June 30, 2013			December 31, 2012
Long-term debt:
Revolving credit facilities	$	2,278,442		$	2,287,942
Term loan credit facilities		814,916			803,002
Long-term debt		3,093,358			3,090,944
Current portion		(150,612	)		(66,656	)
Long-term debt	$	2,942,746		$	3,024,288

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Subsequent events

6 Months Ended

Jun. 30, 2013

Subsequent Events [Abstract]

Subsequent events

15. Subsequent events:

(a) On July 4, 2013, the Company accepted delivery of the MOL Efficiency. The 4600 TEU vessel is on charter to Mitsui O.S.K. Lines Ltd. under a two-year, fixed-rate time charter.

(b) On July 16, 2013, the Company declared quarterly dividends of $0.59375 and $0.496875 per Series C and Series D preferred share, respectively, representing a total distribution of $9,855,000. The dividends were paid on July 30, 2013 to all shareholders of record on July 29, 2013.

(c) On July 19, 2013 the Company entered into contracts for the construction of newbuilding containerships with a major Asian shipbuilder. The vessels are scheduled for delivery in 2015 and have an aggregate purchase price of approximately $550,000,000.

(d) On July 24, 2013, the Company declared a quarterly dividend of $0.3125 per common share. The dividend is payable on August 21, 2013 to all shareholders of record as of August 12, 2013.

(e) On July 25, 2013 the Company entered into a term loan facility with a leading European bank for up to $83,000,000 to fund the construction of one 14000 TEU newbuilidng containership to be chartered to Yang Ming Marine Transport Corp.

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Vessels - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Property Plant And Equipment [Abstract]
Capitalized interest costs to vessels	$ 2,644,000	$ 2,493,000

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Supplemental cash flow information - Schedule of Supplemental Cash Flow Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Supplemental Cash Flow Information [Line Items]
Interest paid on debt	$ 14,313	$ 15,030	$ 30,293	$ 26,337
Interest received	605	12	1,392	246
Undrawn credit facility fee paid	225	338	506	780
Non-cash transactions:
Dividend reinvestment	8,726	916	15,348	5,277	7,168
Other long-term liabilities for vessels under construction				84,787
Long-term debt for vessels under construction	10,040	71,400	26,640	71,400
Acquisition of the Manager for shares, excluding cash received				73,795
Proceeds on sale of vessel		52,104		52,104
Loan repayment for vessels under construction			3,080
Series A preferred shares [Member]
Non-cash transactions:
Dividends on Series A preferred shares	$ 9,423	$ 8,371	$ 18,473	$ 16,499

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Acquisition of Seaspan Management Services Limited - Aggregate Purchase Price (Parenthetical) (Detail)	Jun. 30, 2013
Business Combinations [Abstract]
Business acquisition cost of acquired entity number of shares issued	4,220,728

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Concentrations (Tables)

6 Months Ended

Jun. 30, 2013

Risks And Uncertainties [Abstract]

Schedule of Revenue Derived from Customers

The Company’s revenue is derived from the following customers:

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
COSCON	$	74,671	$	72,584	$	149,268	$	129,786
CSCL Asia		34,645		38,877		69,242		78,678
K-Line		18,984		18,983		37,762		37,969
HL USA		14,739		14,697		29,319		29,176
Other		24,747		22,496		47,119		45,460
	$	167,786	$	167,637	$	332,710	$	321,069

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Financial instruments (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Disclosures [Abstract]

Schedule of Outstanding Interest Rate Derivatives

As of June 30, 2013, the Company had the following outstanding interest rate derivatives:

Fixed per annum rate swapped for LIBOR	Notional amount as of June 30, 2013	Maximum notional amount (1)	Effective date	Ending date
5.6400%	$714,500	$714,500	August 31, 2007		August 31,  2017	(2)
5.1750%	607,149	663,399	July 16, 2012		July 15, 2016
5.4200%	438,462	438,462	September 6, 2007		May 31, 2024
5.6000%	194,000	200,000	June 23, 2010		December 23,  2021	(2)
5.0275%	111,000	158,000	May 31, 2007		September 30, 2015
5.5950%	106,800	106,800	August 28, 2009		August 28, 2020
5.2600%	106,800	106,800	July 3, 2006		February 26,  2021	(2) (3)
5.2000%	90,240	96,000	December 18, 2006		October 2, 2015
5.4975%	59,700	59,700	July 31, 2012		July 31, 2019
5.1700%	24,000	55,500	April 30, 2007		May 29, 2020
5.8700%	—	620,390	August 31, 2017		November 28, 2025

⁽¹⁾  Over the term of the interest rate swaps, the notional amounts increase and decrease. These amounts represent the peak notional during the term of the swap.

⁽²⁾  Prospectively de-designated as an accounting hedge in 2008.

⁽³⁾  The Company has entered into a swaption agreement with a bank (Swaption Counterparty A) whereby Swaption Counterparty A has the option to require the Company to enter into an interest rate swap to pay LIBOR and receive a fixed rate of 5.26%. This is a European option and is open for a two hour period on February 26, 2014 after which it expires. The notional amount of the underlying swap is $106,800,000 with an effective date of February 28, 2014 and an expiration date of February 26, 2021. If Swaption Counterparty A exercises the swaption, the underlying swap effectively will offset the Company’s 5.26% pay fixed LIBOR swap from February 28, 2014 to February 26, 2021.

Schedule of Interest Rate Derivatives

The following provides information about the Company’s interest rate derivatives:

Fair value of asset and liability derivatives:

	June 30, 2013		December 31, 2012
Fair value of financial instruments asset	$	52,143	$	41,031
Fair value of financial instruments liability		485,995		606,740

The following table provides information about losses included in net earnings and reclassified from accumulated other comprehensive loss (“AOCL”) into earnings:

	Three months ended June 30,						Six months ended June 30,
	2013			2012			2013			2012
Gain/(Loss) on derivatives recognized in net earnings:
Change in fair value of financial instruments	$	71,193		$	(82,084	)	$	68,527		$	(86,760	)
Loss reclassified from AOCL to net earnings(1)
Interest expense		(1,384	)		(2,194	)		(2,963	)		(4,736	)
Depreciation and amortization		(219	)		(218	)		(442	)		(384	)

⁽¹⁾  The effective portion of changes in unrealized loss on interest rate swaps was recorded in accumulated other comprehensive income until September 30, 2008 when these contracts were de-designated as accounting hedges. The amounts in accumulated other comprehensive income will be recognized in earnings when and where the previously hedged interest is recognized in earnings.

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Deferred charges

6 Months Ended

Jun. 30, 2013

Text Block [Abstract]

Deferred charges

5. Deferred charges:

	Dry-docking			Financing fees			Total
December 31, 2012	$	12,694		$	31,122		$	43,816
Cost incurred		1,193			16,355			17,548
Amortization expensed		(1,806	)		(4,376	)		(6,182	)
Amortization capitalized		—			(477	)		(477	)
June 30, 2013	$	12,081		$	42,624		$	54,705

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Financial instruments - Schedule of Interest Rate Derivatives (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Fair value of asset and liability derivatives:
Fair value of financial instruments asset	$ 52,143		$ 52,143		$ 41,031
Fair value of financial instruments liability	485,995		485,995		606,740
Gain/(Loss) on derivatives recognized in net earnings:
Change in fair value of financial instruments	71,193	(82,084)	68,527	(86,760)
Interest expense [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Loss reclassified from AOCL to net earnings
Depreciation and amortization / Interest expense	(1,384)	(2,194)	(2,963)	(4,736)
Depreciation and amortization [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Loss reclassified from AOCL to net earnings
Depreciation and amortization / Interest expense	$ (219)	$ (218)	$ (442)	$ (384)

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Share capital (Tables)

6 Months Ended

Jun. 30, 2013

Equity [Abstract]

Schedule of Preferred Shares Outstanding

The Company had the following preferred shares outstanding:

					Liquidation preference
	Shares				June 30,		December 31,
Series	Authorized		Issued		2013		2012
A		315,000		200,000	$	324,345	$	305,872
B		260,000		—		—		—
C		40,000,000		14,000,000		350,000		350,000
D		20,000,000		3,105,000		77,625		77,625
R		1,000,000		—		—		—

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Related party transactions - Schedule of Costs Incurred with Related Parties (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Arrangement fees [Member]
Related Party Transaction [Line Items]
Costs incurred with the Manager and parties related thereto	$ 1,512		$ 4,564
Transaction fees [Member]
Related Party Transaction [Line Items]
Costs incurred with the Manager and parties related thereto	653		1,513
Reimbursed expenses [Member]
Related Party Transaction [Line Items]
Costs incurred with the Manager and parties related thereto	$ 18		$ 36

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Share capital

6 Months Ended

Jun. 30, 2013

Equity [Abstract]

Share capital

8. Share capital:

Preferred shares:

The Company had the following preferred shares outstanding:

					Liquidation preference
	Shares				June 30,		December 31,
Series	Authorized		Issued		2013		2012
A		315,000		200,000	$	324,345	$	305,872
B		260,000		—		—		—
C		40,000,000		14,000,000		350,000		350,000
D		20,000,000		3,105,000		77,625		77,625
R		1,000,000		—		—		—

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Vessels

6 Months Ended

Jun. 30, 2013

Property Plant And Equipment [Abstract]

Vessels

4. Vessels:

June 30, 2013	Cost		Accumulated depreciation		Net book value
Vessels	$	5,365,016	$	636,752	$	4,728,264
Vessels under construction		174,650		—		174,650
Vessels	$	5,539,666	$	636,752	$	4,902,914

December 31, 2012	Cost		Accumulated depreciation		Net book value
Vessels	$	5,339,550	$	553,582	$	4,785,968
Vessels under construction		77,305		—		77,305
Vessels	$	5,416,855	$	553,582	$	4,863,273

During the six months ended June 30, 2013, the Company capitalized interest costs of $2,644,000 (June 30, 2012 - $2,493,000) to vessels under construction.

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Interim Consolidated Statements of Shareholders' Equity (Parenthetical) (Class A common shares [Member], USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Class A common shares [Member]
Dividend on common shares, per share	$ 0.5625	$ 0.9375

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Share-based compensation - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended		1 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Phantom share units [Member]	Dec. 31, 2012 Phantom share units [Member]	Mar. 27, 2013 Stock appreciation rights (SARs) [Member]	Jun. 30, 2013 Stock appreciation rights (SARs) [Member]	Jun. 30, 2012 Stock appreciation rights (SARs) [Member]	Jun. 30, 2013 Stock appreciation rights (SARs) [Member] Tranches	Jun. 30, 2012 Stock appreciation rights (SARs) [Member]	Jun. 30, 2013 Restricted share units and phantom share units [Member]	Jun. 30, 2012 Restricted share units and phantom share units [Member]	Jun. 30, 2013 Restricted share units and phantom share units [Member]	Jun. 30, 2012 Restricted share units and phantom share units [Member]	Jun. 30, 2013 Other Stock Based Awards [Member]	Jun. 30, 2012 Other Stock Based Awards [Member]	Jun. 30, 2013 Other Stock Based Awards [Member]	Jun. 30, 2012 Other Stock Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding phantom share units vested and available for exchange						460,000	328,000
Remaining shares available for issuance						738,514	884,319
Company granted stock appreciation rights			1,664,457			95,000		1,664,457			1,664,457
Number of tranches											3
Tranche share price description											If the fair market value of the common shares equals or exceeds the applicable base price for each tranche for any 20 consecutive trading days on or before the expiration date of each tranche.
Retention requirement description											The common shares received on the exercise of SARs are subject to a retention requirement where the Participant is required to retain ownership of 50% of the net after tax number of shares until the later of March 22, 2018 or 120 days after the exercise date.
Share-based compensation expense									$ 5,780,000		$ 7,842,000		$ 701,000	$ 656,000	$ 1,300,000	$ 1,404,000	$ 150,000	$ 188,000	$ 300,000	$ 375,000
Accelerated share-based compensation expense									2,550,000		2,550,000
Share-based compensation	6,630,000	1,943,000	9,441,000	2,529,000													0		0	0
Share-based compensation capitalized to vessels under construction recognized																	382,000		756,000	184,000
Total fair value of shares vested	33,000		935,000	563,000
Total fair value of shares cancelled	71,000		71,000
Total unrecognized compensation costs relating to unvested share-based compensation awards and SARS	$ 11,336,000		$ 11,336,000		$ 12,519,000
Recognized compensation costs relating to unvested share-based compensation awards and SARS, weighted average period			20 months

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Long-term debt - Schedule of Long-Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Long-term debt:
Long-term Debt	$ 3,093,358	$ 3,090,944
Current portion	(150,612)	(66,656)
Long-term debt Non Current	2,942,746	3,024,288
Revolving credit facilities [Member]
Long-term debt:
Long-term Debt	2,278,442	2,287,942
Term loan credit facilities [Member]
Long-term debt:
Long-term Debt	$ 814,916	$ 803,002

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Supplemental cash flow information (Tables)

6 Months Ended

Jun. 30, 2013

Supplemental Cash Flow Elements [Abstract]

Schedule of Supplemental Cash Flow Information

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
Interest paid on debt	$	14,313	$	15,030	$	30,293	$	26,337
Interest received		605		12		1,392		246
Undrawn credit facility fee paid		225		338		506		780
Non-cash transactions:
Dividends on Series A preferred shares		9,423		8,371		18,473		16,499
Dividend reinvestment		8,726		916		15,348		5,277
Other long-term liabilities for vessels under construction		—		—		—		84,787
Long-term debt for vessels under construction		10,040		71,400		26,640		71,400
Acquisition of the Manager for shares, excluding cash received		—		—		—		73,795
Proceeds on sale of vessel		—		52,104		—		52,104
Loan repayment for vessels under construction		—		—		3,080		—

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Financial instruments - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Derivative [Line Items]
Fair value, long-term debt	$ 2,671,593,000	$ 2,641,016,000
Fair value, other long-term liabilities	601,687,000	631,041,000
Fair value of assets	52,143,000	41,031,000
Fair value of liabilities	485,995,000	606,740,000
Estimated AOCL expected to be reclassified into earnings	5,724,000
Fair value liability of foreign exchange contract	505,000	12,000
Swaption Counterparty B [Member]
Derivative [Line Items]
Derivative, fixed interest rate	1.183%
Fixed per annum rate swapped for LIBOR	0.50%
Derivative, notional amount	200,000,000
Effective date	Mar. 02, 2017
Ending date	Mar. 02, 2027
Fair value of assets	52,143,000	41,031,000
Fair value of liabilities	41,764,000	30,547,000
Forward contracts [Member]
Derivative [Line Items]
Notional amount on foreign exchange forward contract	$ 14,600,000	$ 7,000,000

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Supplemental cash flow information

6 Months Ended

Jun. 30, 2013

Supplemental Cash Flow Elements [Abstract]

Supplemental cash flow information

11. Supplemental cash flow information:

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
Interest paid on debt	$	14,313	$	15,030	$	30,293	$	26,337
Interest received		605		12		1,392		246
Undrawn credit facility fee paid		225		338		506		780
Non-cash transactions:
Dividends on Series A preferred shares		9,423		8,371		18,473		16,499
Dividend reinvestment		8,726		916		15,348		5,277
Other long-term liabilities for vessels under construction		—		—		—		84,787
Long-term debt for vessels under construction		10,040		71,400		26,640		71,400
Acquisition of the Manager for shares, excluding cash received		—		—		—		73,795
Proceeds on sale of vessel		—		52,104		—		52,104
Loan repayment for vessels under construction		—		—		3,080		—

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Long-term debt

6 Months Ended

Jun. 30, 2013

Debt Disclosure [Abstract]

Long-term debt

7. Long-term debt:

	June 30, 2013			December 31, 2012
Long-term debt:
Revolving credit facilities	$	2,278,442		$	2,287,942
Term loan credit facilities		814,916			803,002
Long-term debt		3,093,358			3,090,944
Current portion		(150,612	)		(66,656	)
Long-term debt	$	2,942,746		$	3,024,288

On January 28, 2013, the Company entered into a LIBOR based term loan facility with an Asian bank of up to $340,000,000 to be used towards the refinancing of existing vessels. The facility bears interest at LIBOR plus a margin. The Company is subject to a commitment fee of 0.4% per annum calculated on the undrawn amount of the loan. At June 30, 2013, no amounts have been drawn under this facility.

On February 28, 2013, the Company entered into two term loans of $4,500,000 each. The proceeds of these term loans were used to fund a portion of the construction cost of two 10000 TEU vessels. The loans are non-interest bearing until the respective delivery dates of the vessels which is expected to be in 2014. Upon delivery of the respective vessels, the loans will begin bearing interest at 6% per annum, payable quarterly, and mature on the third anniversary of the respective delivery date. The Company has an option to extend the term of the loans by two years. The loans will bear interest at 7% per annum, payable quarterly over the extension period.

On April 25, 2013, the Company entered into a term loan facility with an Asian bank for up to $174,000,000 to be used to fund construction of two 14000 TEU newbuilding containerships. Upon drawdown, interest is payable every three or six months calculated at the LIBOR rate for the relevant three or six month period plus a margin. The Company is subject to a commitment fee of 0.75% per annum calculated on the undrawn amount of the loan. At June 30, 2013, no amounts have been drawn under this facility.

On June 20, 2013, the Company entered into a term loan facility with a U.S bank and an Australian bank for up to $30,000,000 to be used to fund the purchase price of two 4600 TEU containerships. Upon drawdown, interest is payable every three months calculated at the LIBOR rate for the relevant three month period plus a margin. At June 30, 2013, no amounts have been drawn under this facility.

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Financial instruments

6 Months Ended

Jun. 30, 2013

Fair Value Disclosures [Abstract]

Financial instruments

14. Financial instruments:

(a) Fair value:

The carrying values of cash and cash equivalents, short-term investments, accounts receivable and accounts payable and accrued liabilities approximate their fair values because of their short term to maturity. As of June 30, 2013, the fair value of the Company’s long-term debt is $2,671,593,000 (December 31, 2012 - $2,641,016,000). As of June 30, 2013, the fair value of the Company’s other long-term liabilities is $601,687,000 (December 31, 2012 - $631,041,000). The fair value of long-term debt and other long-term liabilities are estimated based on expected interest and principal repayments, discounted by forward rates plus a margin appropriate to the credit risk of the Company.

The Company’s interest rate derivative financial instruments are re-measured to fair value at the end of each reporting period. The fair values of the interest rate derivative financial instruments have been calculated by discounting the future cash flow of both the fixed rate and variable rate interest rate payments. The discount rate was derived from a yield curve created by nationally recognized financial institutions adjusted for the associated credit risk. The fair values of the interest rate derivative financial instruments are determined based on inputs that are readily available in public markets or can be derived from information available in publicly quoted markets. Therefore, the Company has categorized the fair value of these derivative financial instruments as Level 2 in the fair value hierarchy.

(b) Interest rate derivative financial instruments:

As of June 30, 2013, the Company had the following outstanding interest rate derivatives:

Fixed per annum rate swapped for LIBOR	Notional amount as of June 30, 2013	Maximum notional amount (1)	Effective date	Ending date
5.6400%	$714,500	$714,500	August 31, 2007		August 31,  2017	(2)
5.1750%	607,149	663,399	July 16, 2012		July 15, 2016
5.4200%	438,462	438,462	September 6, 2007		May 31, 2024
5.6000%	194,000	200,000	June 23, 2010		December 23,  2021	(2)
5.0275%	111,000	158,000	May 31, 2007		September 30, 2015
5.5950%	106,800	106,800	August 28, 2009		August 28, 2020
5.2600%	106,800	106,800	July 3, 2006		February 26,  2021	(2) (3)
5.2000%	90,240	96,000	December 18, 2006		October 2, 2015
5.4975%	59,700	59,700	July 31, 2012		July 31, 2019
5.1700%	24,000	55,500	April 30, 2007		May 29, 2020
5.8700%	—	620,390	August 31, 2017		November 28, 2025

⁽¹⁾  Over the term of the interest rate swaps, the notional amounts increase and decrease. These amounts represent the peak notional during the term of the swap.

⁽²⁾  Prospectively de-designated as an accounting hedge in 2008.

⁽³⁾  The Company has entered into a swaption agreement with a bank (Swaption Counterparty A) whereby Swaption Counterparty A has the option to require the Company to enter into an interest rate swap to pay LIBOR and receive a fixed rate of 5.26%. This is a European option and is open for a two hour period on February 26, 2014 after which it expires. The notional amount of the underlying swap is $106,800,000 with an effective date of February 28, 2014 and an expiration date of February 26, 2021. If Swaption Counterparty A exercises the swaption, the underlying swap effectively will offset the Company’s 5.26% pay fixed LIBOR swap from February 28, 2014 to February 26, 2021.

In addition to the swaps listed above, the Company has entered into swaption agreements with a bank (Swaption Counterparty B) whereby Swaption Counterparty B has the option to require the Company to enter into interest rate swaps, by February 28, 2017, to pay LIBOR and receive a fixed rate of 1.183% and to pay 0.5% and receive LIBOR, respectively. The notional amounts of the underlying swaps are each $200,000,000 with an effective date of March 2, 2017 and an expiration date of March 2, 2027.

The swaption agreements with Swaption Counterparty B are subject to a master netting agreement but are each recorded at the gross amount on the balance sheet. At June 30, 2013, these swaptions had asset and liability values of $52,143,000 and $41,764,000, respectively (December 31, 2012 - asset of $41,031,000 and liability of $30,547,000).

Counterparties to the derivative financial instruments are major financial institutions. Due to the nature of the counterparties and the fact that the instruments were primarily in favor of counterparties at June 30, 2013, the risk of credit loss related to these counterparties is considered to be immaterial at June 30, 2013.

(b) Interest rate derivative financial instruments (continued):

The following provides information about the Company’s interest rate derivatives:

Fair value of asset and liability derivatives:

	June 30, 2013		December 31, 2012
Fair value of financial instruments asset	$	52,143	$	41,031
Fair value of financial instruments liability		485,995		606,740

The following table provides information about losses included in net earnings and reclassified from accumulated other comprehensive loss (“AOCL”) into earnings:

	Three months ended June 30,						Six months ended June 30,
	2013			2012			2013			2012
Gain/(Loss) on derivatives recognized in net earnings:
Change in fair value of financial instruments	$	71,193		$	(82,084	)	$	68,527		$	(86,760	)
Loss reclassified from AOCL to net earnings(1)
Interest expense		(1,384	)		(2,194	)		(2,963	)		(4,736	)
Depreciation and amortization		(219	)		(218	)		(442	)		(384	)

⁽¹⁾  The effective portion of changes in unrealized loss on interest rate swaps was recorded in accumulated other comprehensive income until September 30, 2008 when these contracts were de-designated as accounting hedges. The amounts in accumulated other comprehensive income will be recognized in earnings when and where the previously hedged interest is recognized in earnings.

The estimated amount of AOCL expected to be reclassified to net earnings within the next 12 months is approximately $5,724,000.

(c) Foreign exchange derivative instruments:

We are exposed to market risk from foreign currency fluctuations. We have entered into foreign currency forward contracts to manage foreign currency fluctuations. At June 30, 2013, the notional amount of the foreign exchange forward contracts is $14,600,000 (December 31, 2012 - $7,000,000) and the fair value liability is $505,000 (December 31, 2012 - $12,000).

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Commitments

6 Months Ended

Jun. 30, 2013

Commitments And Contingencies Disclosure [Abstract]

Commitments

12. Commitments:

(a) As of June 30, 2013, based on the contractual delivery dates, the outstanding commitments for the purchase of additional vessels and installment payments for vessels under construction is as follows:

Remainder of 2013	$	44,380
2014		418,640
2015		235,380
	$	698,400

(b) As of June 30, 2013, the minimum future revenues to be received on committed time charter party agreements and interest income from sales-type capital leases are approximately:

Remainder of 2013	$	334,922
2014		693,794
2015		743,864
2016		706,349
2017		636,481
Thereafter		3,041,855
	$	6,157,265

The minimum future revenues are based on 100% utilization, relate to committed time charter party agreements in effect at June 30, 2013 and assume no renewals or extensions.

(c) As of June 30, 2013, the commitment under operating leases is as follows:

Remainder of 2013	$	3,403
2014		6,882
2015		6,893
2016		6,911
2017		6,969
Thereafter		24,088
	$	55,146

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Document and Entity Information	6 Months Ended
	Jun. 30, 2013
Document And Entity Information [Abstract]
Document Type	6-K/A
Amendment Flag	false
Document Period End Date	Jun. 30, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Trading Symbol	SSW
Entity Registrant Name	Seaspan CORP
Entity Central Index Key	0001332639
Current Fiscal Year End Date	--12-31

XML

Concentrations

6 Months Ended

Jun. 30, 2013

Risks And Uncertainties [Abstract]

Concentrations

13. Concentrations:

The Company’s revenue is derived from the following customers:

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
COSCON	$	74,671	$	72,584	$	149,268	$	129,786
CSCL Asia		34,645		38,877		69,242		78,678
K-Line		18,984		18,983		37,762		37,969
HL USA		14,739		14,697		29,319		29,176
Other		24,747		22,496		47,119		45,460
	$	167,786	$	167,637	$	332,710	$	321,069

XML

Financial instruments - Schedule of Outstanding Interest Rate Derivatives (Parenthetical) (Detail) (Swaption Counterparty A [Member], USD $)	6 Months Ended
	Jun. 30, 2013
Swaption Counterparty A [Member]
Derivative [Line Items]
Derivative, notional amount	$ 106,800,000
Fixed per annum rate swapped for LIBOR	5.26%
Effective date	Feb. 28, 2014
Ending date	Feb. 26, 2021

XML

Financial instruments - Schedule of Outstanding Interest Rate Derivatives (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013
5.6400% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.64%
Derivative, notional amount	$ 714,500,000
Effective date	Aug. 31, 2007
Ending date	Aug. 31, 2017
5.1750% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.175%
Derivative, notional amount	607,149,000
Effective date	Jul. 16, 2012
Ending date	Jul. 15, 2016
5.4200% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.42%
Derivative, notional amount	438,462,000
Effective date	Sep. 06, 2007
Ending date	May 31, 2024
5.6000% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.60%
Derivative, notional amount	194,000,000
Effective date	Jun. 23, 2010
Ending date	Dec. 23, 2021
5.0275% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.0275%
Derivative, notional amount	111,000,000
Effective date	May 31, 2007
Ending date	Sep. 30, 2015
5.5950% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.595%
Derivative, notional amount	106,800,000
Effective date	Aug. 28, 2009
Ending date	Aug. 28, 2020
5.2600% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.26%
Derivative, notional amount	106,800,000
Effective date	Jul. 03, 2006
Ending date	Feb. 26, 2021
5.2000% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.20%
Derivative, notional amount	90,240,000
Effective date	Dec. 18, 2006
Ending date	Oct. 02, 2015
5.4975% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.4975%
Derivative, notional amount	59,700,000
Effective date	Jul. 31, 2012
Ending date	Jul. 31, 2019
5.1700% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.17%
Derivative, notional amount	24,000,000
Effective date	Apr. 30, 2007
Ending date	May 29, 2020
5.8700% [Member]
Derivative [Line Items]
Fixed per annum rate swapped for LIBOR	5.87%
Effective date	Aug. 31, 2017
Ending date	Nov. 28, 2025
Maximum [Member] | 5.6400% [Member]
Derivative [Line Items]
Derivative, notional amount	714,500,000
Maximum [Member] | 5.1750% [Member]
Derivative [Line Items]
Derivative, notional amount	663,399,000
Maximum [Member] | 5.4200% [Member]
Derivative [Line Items]
Derivative, notional amount	438,462,000
Maximum [Member] | 5.6000% [Member]
Derivative [Line Items]
Derivative, notional amount	200,000,000
Maximum [Member] | 5.0275% [Member]
Derivative [Line Items]
Derivative, notional amount	158,000,000
Maximum [Member] | 5.5950% [Member]
Derivative [Line Items]
Derivative, notional amount	106,800,000
Maximum [Member] | 5.2600% [Member]
Derivative [Line Items]
Derivative, notional amount	106,800,000
Maximum [Member] | 5.2000% [Member]
Derivative [Line Items]
Derivative, notional amount	96,000,000
Maximum [Member] | 5.4975% [Member]
Derivative [Line Items]
Derivative, notional amount	59,700,000
Maximum [Member] | 5.1700% [Member]
Derivative [Line Items]
Derivative, notional amount	55,500,000
Maximum [Member] | 5.8700% [Member]
Derivative [Line Items]
Derivative, notional amount	$ 620,390,000