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Senior Notes (Details) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	Aug. 20, 2018	Jul. 16, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Senior Notes [Line Items]
Principal Amount, Net of Unamortized Deferred Financing Costs			$ 2,451,886		$ 2,451,886		$ 2,448,439
Loss on extinguishment of debt			0	$ 26,722	0	$ 26,722
Accelerated unamortized deferred financing costs					0	6,334
Interest costs capitalized			$ 4,200	$ 5,200	$ 14,100	$ 15,700
6.125% Senior Notes due 2022 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage			6.125%		6.125%
Principal amount			$ 476,796		$ 476,796		476,796
Unamortized deferred financing costs			(3,170)		(3,170)		(3,921)
Principal Amount, Net of Unamortized Deferred Financing Costs			$ 473,626		$ 473,626		472,875
5.0% Senior Notes due 2024 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage			5.00%		5.00%
Principal amount			$ 500,000		$ 500,000		500,000
Unamortized deferred financing costs			(3,996)		(3,996)		(4,688)
Principal Amount, Net of Unamortized Deferred Financing Costs			$ 496,004		$ 496,004		495,312
5.625% Senior Notes due 2025 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage			5.625%		5.625%
Principal amount			$ 500,000		$ 500,000		500,000
Unamortized deferred financing costs			(5,130)		(5,130)		(5,808)
Principal Amount, Net of Unamortized Deferred Financing Costs			$ 494,870		$ 494,870		494,192
6.75% Senior Notes due 2026 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage			6.75%		6.75%
Principal amount			$ 500,000		$ 500,000		500,000
Unamortized deferred financing costs			(5,780)		(5,780)		(6,407)
Principal Amount, Net of Unamortized Deferred Financing Costs			$ 494,220		$ 494,220		493,593
6.625% Senior Notes due 2027 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage			6.625%		6.625%
Principal amount	$ 500,000		$ 500,000		$ 500,000		500,000
Unamortized deferred financing costs			(6,834)		(6,834)		(7,533)
Principal Amount, Net of Unamortized Deferred Financing Costs			493,166		493,166		492,467
Senior Notes issuance proceeds, net of deferred financing costs	492,100
Deferred financing costs	$ 7,900
Senior Notes
Senior Notes [Line Items]
Principal amount			2,476,796		2,476,796		2,476,796
Unamortized deferred financing costs			(24,910)		(24,910)		(28,357)
Principal Amount, Net of Unamortized Deferred Financing Costs			$ 2,451,886		$ 2,451,886		$ 2,448,439
6.50% Senior Notes Due 2021 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage		6.50%
Total cash consideration paid to repurchase debt, including accrued interest		$ 355,900
6.50% Senior Notes Due 2023 [Member]
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage				6.50%		6.50%
Q3 2018 Senior Notes Transactions [Member]
Senior Notes [Line Items]
Total cash consideration paid to repurchase debt, including accrued interest				$ 497,800
Loss on extinguishment of debt				26,700
Premiums paid for debt extinguishment				20,400
Accelerated unamortized deferred financing costs				$ 6,300

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