Long-Term Debt (Tables)

6 Months Ended

Jun. 30, 2015

Debt Disclosure [Abstract]

Schedule of Line of Credit Facilities [Table Text Block]

The following table presents the outstanding balance, total amount of letters of credit, and available borrowing capacity under the Credit Agreement as of July 22, 2015, June 30, 2015, and December 31, 2014:

	As of July 22, 2015		As of June 30, 2015		As of December 31, 2014
	(in thousands)
Credit facility balance	$	175,000	$	122,000	$	166,000
Letters of credit (1)	$	200	$	200	$	808
Available borrowing capacity	$	1,324,800	$	1,377,800	$	1,333,192

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⁽¹⁾ Letters of credit reduce the amount available under the credit facility on a dollar-for-dollar basis.

Schedule of Long-term Debt Instruments [Table Text Block]

The Senior Notes line on the accompanying balance sheets represents the outstanding principal amount of the notes shown in the table below (the “Senior Notes”):

	As of June 30, 2015		As of December 31, 2014
	(in thousands)
6.625% Senior Notes due 2019	$	—	$	350,000
6.50% Senior Notes due 2021	350,000		350,000
6.125% Senior Notes due 2022	600,000		600,000
6.50% Senior Notes due 2023	400,000		400,000
5.0% Senior Notes due 2024	500,000		500,000
5.625% Senior Notes due 2025	500,000		—
Total Senior Notes	$	2,350,000	$	2,200,000

Debt Instrument Redemption [Table Text Block]

On or after June 1, 2020, the Company may also redeem all or, from time to time during the twelve-month period beginning on June 1 of each applicable year, a portion of the 2025 Notes at the redemption prices set forth below expressed as a percentage of the principal amount redeemed, plus accrued and unpaid interest:

2020	102.813	%
2021	101.875	%
2022	100.938	%
2023 and thereafter	100.000	%