Other Financial Statement Disclosures - Long Term Debt (Details) - USD ($)	Jun. 30, 2017	Jan. 09, 2017	Dec. 31, 2016	Mar. 31, 2016
Debt Instrument [Line Items]
Total carrying value	$ 2,516,600,000		$ 2,680,200,000
Current portion of long-term debt	0		126,800,000
Carrying value, less current portion	2,516,600,000		2,553,400,000
Subject Notes [Member] | 5% Senior Notes, due September 2017 [Member]
Debt Instrument [Line Items]
Total carrying value	$ 0		$ 92,000,000
Stated rate	5.00%		5.00%	5.00%
Principal amount		$ 92,100,000.0	$ 92,200,000.0
Effective rate			5.20%
Subject Notes [Member] | 7.875% Senior Notes, due August 2019 [Member]
Debt Instrument [Line Items]
Total carrying value	$ 207,200,000		$ 208,900,000
Stated rate	7.875%		7.875%	7.875%
Principal amount	$ 207,900,000.0		$ 209,800,000.0
Effective rate	8.00%		8.00%
Subject Notes [Member] | 4.875% Senior Notes, due June 2022 [Member]
Debt Instrument [Line Items]
Total carrying value	$ 625,100,000		$ 695,400,000
Stated rate	4.875%		4.875%
Principal amount	$ 620,800,000.0		$ 690,200,000.0
Effective rate	4.70%		4.70%
Subject Notes [Member] | 4.75% Senior Notes, due January 2024 [Member]
Debt Instrument [Line Items]
Total carrying value	$ 395,800,000		$ 395,600,000
Stated rate	4.75%		4.75%
Principal amount	$ 398,100,000.0		$ 398,100,000.0
Effective rate	4.80%		4.80%
Subject Notes [Member] | 7.375% Senior Note Payable Due June 2025 [Member]
Debt Instrument [Line Items]
Total carrying value	$ 497,300,000		$ 497,200,000
Stated rate	7.375%		7.375%
Principal amount	$ 500,000,000.0		$ 500,000,000.0
Effective rate	7.40%		7.40%
Subject Notes [Member] | 5.4% Senior Notes due, December 2042 [Member]
Debt Instrument [Line Items]
Total carrying value	$ 395,000,000		$ 394,900,000
Stated rate	5.40%		5.40%
Principal amount	$ 400,000,000.0		$ 400,000,000
Effective rate	5.40%		5.40%
Subject Notes [Member] | 5.85% Senior Notes, due January 2044 [Member]
Debt Instrument [Line Items]
Total carrying value	$ 396,200,000		$ 396,200,000
Stated rate	5.85%		5.85%
Principal amount	$ 400,000,000		$ 400,000,000
Effective rate	5.90%		5.90%