Represents charges to interest expense related to the extinguishment of borrowing before maturity.

No definition available.

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- Definition

Repayments of notes payable at maturity.

+ References

No definition available.

+ Details

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- Definition

The charge to earnings for the amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized in conjunction with early debt extinguishment.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Balance Type:	na
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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.

+ Details

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- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from the issuance of long-term debt that is not secured by collateral. Excludes proceeds from tax exempt unsecured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow for a borrowing supported by a written promise to pay an obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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Period Type:	duration

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- Details

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Debt - Notes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Repayments of notes payable	$ 497,975	$ 1,500,000	$ 300,000
Unsecured Debt [Member]
Debt Instrument [Line Items]
Write off of deferred debt issuance cost		1,900
Write off unamortized (premium) discount		25,200
5.75 % Notes [Member]
Debt Instrument [Line Items]
Repayments of notes payable	$ 394,100
Debt instrument, interest rate, stated percentage	5.75%
7.125% Notes [Member]
Debt Instrument [Line Items]
Repayments of notes payable	$ 103,900	$ 46,100
Debt instrument, interest rate, stated percentage	7.125%	7.125%
Prepayment penalty charges		$ 4,600
3.25% Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.25%
Proceeds from issuance of unsecured debt	$ 400,000
Proceeds from debt, net of issuance costs	$ 399,300
Debt instrument, interest rate, effective percentage	3.32%
4.00% Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.00%
Proceeds from issuance of unsecured debt	$ 300,000
Proceeds from debt, net of issuance costs	$ 293,200
Debt instrument, interest rate, effective percentage	4.11%
5.125% Notes [Member]
Debt Instrument [Line Items]
Repayments of notes payable		$ 228,900
Debt instrument, interest rate, stated percentage		5.125%
Prepayment penalty charges		$ 1,400
Repayments of notes payable at maturity		271,100
5.375% Notes [Member]
Debt Instrument [Line Items]
Repayments of notes payable		$ 400,000
Debt instrument, interest rate, stated percentage		5.375%
Prepayment penalty charges		$ 9,500
5.750% Notes [Member]
Debt Instrument [Line Items]
Repayments of notes payable		$ 255,900
Debt instrument, interest rate, stated percentage		5.75%
Prepayment penalty charges		$ 16,500
4.625% Notes [Member]
Debt Instrument [Line Items]
Repayments of notes payable		$ 250,000
Debt instrument, interest rate, stated percentage		4.625%
Prepayment penalty charges		$ 31,600
7.570% Notes [Member]
Debt Instrument [Line Items]
Repayments of notes payable		$ 48,000
Debt instrument, interest rate, stated percentage		7.57%
Prepayment penalty charges		$ 19,300
2.85% Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage		2.85%
Proceeds from issuance of unsecured debt		$ 500,000
Proceeds from debt, net of issuance costs		$ 496,700
Debt instrument, interest rate, effective percentage		3.10%