Represents the percentage of debt discount that was originally recognized at the issuance of the instrument.

No definition available.

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- Definition

Debt Issuance Cost Amortization Period

+ References

No definition available.

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- Definition

Percentage of Underwriting Fee

+ References

No definition available.

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- Definition

Represents the percentage of principal amount used in computation of the redemption price to be paid on conversion of convertible notes at the request of the debt holders and upon the occurrence of a designated event.

+ References

No definition available.

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- Definition

Represents the number of days of written notice to be made to the holders of the notes required for redemption.

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No definition available.

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- Definition

Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

+ References

No definition available.

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- Definition

Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

+ References

No definition available.

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- Definition

Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature.

+ References

No definition available.

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
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-Subparagraph e
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- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Amount, after accumulated amortization, of debt discount.

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

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Exchangeable Senior Notes - Additional Information (Detail)			1 Months Ended	6 Months Ended
	Jul. 05, 2018 USD ($)	Jun. 21, 2013 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2018 USD ($) d	Dec. 31, 2017 USD ($)
Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes)
Debt Instrument [Line Items]
Effective interest rate on the liability component				4.00%
Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes)
Debt Instrument [Line Items]
Notes exchange, threshold percentage				130.00%
Notes exchange, threshold trading days \| d				20
Notes exchange, threshold consecutive trading days \| d				30
Effective interest rate on the liability component				4.00%
Operating Partnership
Debt Instrument [Line Items]
Related debt issuance costs				$ 5,407,000	$ 6,620,000
Operating Partnership \| Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes)
Debt Instrument [Line Items]
Principal amount of notes issued			$ 575,000,000
Debt stated interest rate			3.125%	3.125%
Related debt issuance costs			$ 11,992,000
Underwriting fee percentage			2.00%
Amortization period			5 years
Conversion ratio				0.01071
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest			100.00%
Redemption price as percentage of principal amount of notes at request of debt holders and upon occurrence of designated event			100.00%
Operating Partnership \| Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) \| Minimum
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption			30 days
Operating Partnership \| Exchangeable Senior Notes 3.125% due 2035 (the 2015 Notes) \| Maximum
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption			60 days
Operating Partnership \| Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes)
Debt Instrument [Line Items]
Principal amount of notes issued		$ 250,000,000
Debt stated interest rate		2.375%		2.375%
Related debt issuance costs		$ 1,672,000		$ 10,000
Conversion ratio				0.01902
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest		100.00%
Redemption price as percentage of principal amount of notes at request of debt holders and upon occurrence of designated event		100.00%
Discount rate		1.50%
Unamortized cash discount		$ 3,750,000		$ 230,000
Amortization period		5 years
Principal amount repurchased				37,709,000
Total consideration paid for repurchase				$ 58,469,000
Operating Partnership \| Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) \| Minimum
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption		30 days
Operating Partnership \| Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes) \| Maximum
Debt Instrument [Line Items]
Number of days of written notice to holders of notes required for redemption		60 days
Subsequent Event [Member] \| Operating Partnership \| Exchangeable Senior Notes 2.375% due 2033 (the 2013 Notes)
Debt Instrument [Line Items]
Total consideration paid for repurchase	$ 21,801,000