Long-Term Debt (Tables)

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

Schedule of Credit Agreement Facilities [Table Text Block]

The following table presents the outstanding balance, total amount of letters of credit outstanding, and available borrowing capacity under the Credit Agreement as of July 25, 2018, June 30, 2018, and December 31, 2017:

	As of July 25, 2018		As of June 30, 2018		As of December 31, 2017
	(in thousands)
Credit facility balance (1)	$	—	$	—	$	—
Letters of credit (2)	200		200		200
Available borrowing capacity	999,800		999,800		924,800
Total aggregate lender commitment amount	$	1,000,000	$	1,000,000	$	925,000

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⁽¹⁾  Unamortized deferred financing costs attributable to the credit facility are presented as a component of other noncurrent assets on the accompanying balance sheets and totaled $2.4 million and $3.1 million as of June 30, 2018, and December 31, 2017, respectively.

⁽²⁾  Letters of credit outstanding reduce the amount available under the credit facility on a dollar-for-dollar basis.

Schedule of Senior Notes [Table Text Block]

The current portion of Senior Notes, net of unamortized deferred financing costs and noncurrent portion of Senior Notes, net of unamortized deferred financing costs lines on the accompanying balance sheets as of June 30, 2018, and December 31, 2017, consisted of the following:

	As of June 30, 2018						As of December 31, 2017
	Principal Amount		Unamortized Deferred Financing Costs		Senior Notes, Net of Unamortized Deferred Financing Costs		Principal Amount		Unamortized Deferred Financing Costs		Senior Notes, Net of Unamortized Deferred Financing Costs
	(in thousands)
6.50% Senior Notes due 2021	$	344,611	$	2,310	$	342,301	$	344,611	$	2,656	$	341,955
6.125% Senior Notes due 2022	561,796		5,211		556,585		561,796		5,800		555,996
6.50% Senior Notes due 2023	394,985		3,342		391,643		394,985		3,707		391,278
5.0% Senior Notes due 2024	500,000		5,149		494,851		500,000		5,610		494,390
5.625% Senior Notes due 2025	500,000		6,261		493,739		500,000		6,714		493,286
6.75% Senior Notes due 2026	500,000		6,824		493,176		500,000		7,242		492,758
Total	$	2,801,392	$	29,097	$	2,772,295	$	2,801,392	$	31,729	$	2,769,663

Schedule of Senior Convertible Notes [Table Text Block]

The Senior Convertible Notes, net of unamortized discount and deferred financing costs line on the accompanying balance sheets as of June 30, 2018, and December 31, 2017, consisted of the following:

	As of June 30, 2018			As of December 31, 2017
	(in thousands)
Principal amount of Senior Convertible Notes	$	172,500		$	172,500
Unamortized debt discount	(26,319		)	(30,183		)
Unamortized deferred financing costs	(2,751		)	(3,210		)
Senior Convertible Notes, net of unamortized discount and deferred financing costs	$	143,430		$	139,107