Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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Long-Term Debt (Narrative) (Details) - USD ($)					1 Months Ended	3 Months Ended			6 Months Ended		12 Months Ended
Long-Term Debt (Narrative) (Details) - USD ($)	May. 06, 2015	Dec. 31, 2014	Dec. 15, 2014	Jul. 02, 2012	Dec. 31, 2015	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Jun. 30, 2015	Mar. 09, 2015	Jan. 23, 2015	Aug. 13, 2012
Debt Instrument [Line Items]
Outstanding letters of credit					$ 9,200,000	$ 9,200,000			$ 9,200,000
Redemption of notes									8,300,000	$ 259,700,000
Redemption premium								$ 23,800,000		23,800,000
Debt obligations					3,744,100,000	3,744,100,000			3,744,100,000		$ 3,752,400,000
Loss on extinguishment of debt								30,900,000		30,900,000
Debt issuance cost									99,500,000
Unamortized debt issuance cost		$ 7,100,000			66,200,000	66,200,000		7,100,000	66,200,000	7,100,000	71,000,000
Accumulated amortization					33,300,000	33,300,000			33,300,000		28,300,000
Unamortized debt issuance related interest						2,500,000		3,800,000	$ 5,000,000	7,500,000
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Notional amount of derivative														$ 750,000,000
Derivative, maturity date									Jun. 30, 2017
Derivative, fixed interest rate														1.67%
Derivative, floor rate														1.25%
Change in fair value of interest rate swap						(1,000,000)		1,500,000	$ (600,000)	$ (500,000)
Interest Rate Derivative Liabilities, at Fair Value					$ 3,500,000	$ 3,500,000			$ 3,500,000		$ 4,100,000
Revolver [Member]
Debt Instrument [Line Items]
Percentage of excess revolver committed to debt payments									35.00%
Total indebtedness ratio					5.25%	5.25%			5.25%
Standby Letter Of Credit [Member]
Debt Instrument [Line Items]
Unused commitment, percentage									0.25%
Secured Debt [Member] \| Revolver [Member]
Debt Instrument [Line Items]
Line of credit facility maturity date									Apr. 17, 2020
Outstanding letters of credit increased					$ 50,000,000	$ 50,000,000			$ 50,000,000
Outstanding letters of credit					0	0			0
Available borrowing capacity					$ 440,800,000	$ 440,800,000			$ 440,800,000
Term Loan Facility due 2021 [Member]
Debt Instrument [Line Items]
Percentage of effective interest rate					3.75%	3.75%			3.75%		3.75%
Maturity date									2021		2021
Debt obligations					$ 1,638,500,000	$ 1,638,500,000			$ 1,638,500,000		$ 1,646,800,000
2020 Unsecured Notes [Member]
Debt Instrument [Line Items]
Secured debt ratio					4.50	4.50			4.50
Total indebtedness ratio					5.25%	5.25%			5.25%
Unsecured Debt [Member]
Debt Instrument [Line Items]
Premium on debt being accreted					$ 6,700,000	$ 6,700,000			$ 6,700,000		7,100,000
2023 Unsecured Notes [Member]
Debt Instrument [Line Items]
Secured debt ratio					4.50	4.50			4.50
Total indebtedness ratio					6.00%	6.00%			6.00%
2025 Unsecured Notes [Member]
Debt Instrument [Line Items]
Secured debt ratio					4.50	4.50			4.50
Total indebtedness ratio					6.00%	6.00%			6.00%
Unamortized Debt Issuance Costs
Debt Instrument [Line Items]
Loss on extinguishment of debt											$ 23,200,000
Minimum [Member] \| Secured Debt [Member] \| Revolver [Member]
Debt Instrument [Line Items]
Unused commitment, percentage									0.25%
Maximum [Member] \| Secured Debt [Member] \| Revolver [Member]
Debt Instrument [Line Items]
Unused commitment, percentage									0.375%
Amendment and Restatement Agreement [Member] \| Term Loan Facility
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity	$ 450,000,000
Payment towards principal	$ 4,100,000
Percentage of excess cash flows committed to debt payments	50.00%
10.125% Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount				$ 500,000,000
Interest rate				10.125%
Maturity date				2020
Redemption premium								$ 23,800,000
10.125% Senior Notes due 2020 [Member] \| Unsecured Debt [Member]
Debt Instrument [Line Items]
Interest rate					10.125%	10.125%			10.125%		10.125%
Maturity date									2020		2020
Redemption of notes			$ 174,400,000
Debt obligations					$ 325,600,000	$ 325,600,000			$ 325,600,000		$ 325,600,000
10.125% Senior Notes due 2020 [Member] \| Unsecured Debt [Member] \| December 15, 2014 [Member]
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage			110.125%
8.125% Senior Secured Notes [Member]
Debt Instrument [Line Items]
Redemption of notes			$ 75,000,000
8.125% Senior Secured Notes [Member] \| December 15, 2014 [Member]
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		108.125%
8.125% Senior Secured Notes [Member] \| Secured Debt [Member]
Debt Instrument [Line Items]
Interest rate							8.125%
Maturity date						2020
Redemption of notes							$ 675,000,000
Redemption premium							$ 38,800,000
8.125% Senior Secured Notes [Member] \| Secured Debt [Member] \| Second Note Redemption [Member]
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage							105.75%
January Notes Offering [Member]
Debt Instrument [Line Items]
Debt instrument, face amount													$ 700,000,000
March Notes Offering [Member]
Debt Instrument [Line Items]
Debt instrument, face amount												$ 730,000,000
Debt Instrument Issuance At Premium Price Percentage						1.00%
Premium on debt being accreted					$ 7,300,000	$ 7,300,000			7,300,000
6.00% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Cumulative proceeds from issuance of private placement									$ 1,437,300,000
6.00% Senior Notes due 2023 [Member] \| Unsecured Debt [Member]
Debt Instrument [Line Items]
Line of credit facility maturity date									Apr. 01, 2023
Interest rate					6.00%	6.00%			6.00%		6.00%	6.00%
Maturity date						2023			2023		2023
Debt obligations					$ 1,430,000,000	$ 1,430,000,000			$ 1,430,000,000		$ 1,430,000,000
6.375% Senior Notes due 2025 [Member] \| Unsecured Debt [Member]
Debt Instrument [Line Items]
Line of credit facility maturity date	May 15, 2025
Debt instrument, face amount	$ 350,000,000
Interest rate					6.375%	6.375%			6.375%		6.375%
Maturity date					2025				2025		2025
Debt obligations	344,500,000				$ 350,000,000	$ 350,000,000			$ 350,000,000		$ 350,000,000
Loss on extinguishment of debt	$ 8,400,000
LIBOR [Member] \| Term Loan Facility due 2021 [Member]
Debt Instrument [Line Items]
Revolver interest rate									2.75%
LIBOR [Member] \| Minimum [Member] \| Secured Debt [Member] \| Revolver [Member]
Debt Instrument [Line Items]
Revolver interest rate									2.00%
LIBOR [Member] \| Maximum [Member] \| Secured Debt [Member] \| Revolver [Member]
Debt Instrument [Line Items]
Revolver interest rate									3.00%
LIBOR [Member] \| Amendment and Restatement Agreement [Member] \| Term Loan Facility
Debt Instrument [Line Items]
Interest rate decrease	25.00%
Revolver interest rate	2.75%
LIBOR [Member] \| Amendment and Restatement Agreement [Member] \| Minimum [Member] \| Term Loan Facility
Debt Instrument [Line Items]
Revolver interest rate	1.00%