Debt (Schedule of Obligations Under Debt Arrangements) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 11, 2017	May 21, 2015	May 15, 2014
Debt Instrument [Line Items]
Senior secured credit facility	$ 959,300,000	$ 970,100,000
Unamortized discount an debt issuance costs	30,063,000	37,637,000
Senior unsecured notes, net of debt issuance costs	2,469,937,000	2,462,363,000
Long-term debt, principal	3,459,300,000	3,470,100,000
Total long-term debt, net value	3,429,237,000	3,432,463,000
6.750% senior unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes, principal	750,000,000	750,000,000
Unamortized discount an debt issuance costs	9,349,000	12,763,000
Senior unsecured notes, net of debt issuance costs	740,651,000	737,237,000
6.000% senior unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes, principal	400,000,000	400,000,000		$ 400,000,000
Unamortized discount an debt issuance costs	3,557,000	4,624,000
Senior unsecured notes, net of debt issuance costs	396,443,000	395,376,000
5.625% senior unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes, principal	350,000,000	350,000,000			$ 350,000,000
Unamortized discount an debt issuance costs	3,923,000	4,820,000
Senior unsecured notes, net of debt issuance costs	346,077,000	345,180,000
6.500% senior unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes, principal	550,000,000	550,000,000
Unamortized discount an debt issuance costs	7,020,000	8,241,000
Senior unsecured notes, net of debt issuance costs	542,980,000	541,759,000
6.250% senior unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes, principal	450,000,000	450,000,000	$ 450,000,000
Unamortized discount an debt issuance costs	6,214,000	7,189,000
Senior unsecured notes, net of debt issuance costs	443,786,000	442,811,000
Senior secured credit facility
Debt Instrument [Line Items]
Unamortized discount an debt issuance costs	7,600,000	10,800,000
Line of Credit
Debt Instrument [Line Items]
Unamortized discount an debt issuance costs	$ 0	$ 0