Senior Debt (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Covenants [Abstract]
Outstanding indebtedness less cash in excess of	$ 25,000,000	$ 25,000,000
Consolidated funded debt outstanding	819,000,000	819,000,000
Consolidated EBITDA		315,700,000
Consolidated senior secured debt outstanding	269,000,000	269,000,000
Adjusted consolidated EBITDA		558,800,000
Consolidated fixed charges		285,400,000
Financial Covenants Ratios (Table Details) [Abstract]
Required consolidated total leverage ratio, maximum	4.50	4.50
Actual consolidated total leverage ratio	2.59	2.59
Required consolidated senior secured leverage ratio, maximum	2.75	2.75
Actual consolidated senior secured leverage ratio	0.85	0.85
Required consolidated fixed charge coverage ratio, minimum	1.5	1.5
Actual consolidated fixed charge coverage ratio	1.96	1.96
Interest Rate [Abstract]
Interest rate terms	Borrowings under the Revolving Facility bear interest at varying rates equal to either the Eurodollar rate plus 1.50% to 2.75%, or the ABR rate plus 0.50% to 1.75%, at our election.
Commitment fee percentage, minimum	0.30%
Commitment fee percentage, maximum	0.50%
Commitment fee percentage, actual	0.45%
Senior Debt (Details) [Abstract]
Event of default-3rd party ownership % of our voting stock	35.00%	35.00%
Event of default-not satisfied or bonded judgment in excess of	50,000,000	50,000,000
Maximum period allowed for pending judgment to satisfy or bond (in days)	30	30
Debt Instrument [Line Items]
Senior credit facilities, maximum amount	900,000,000	900,000,000
Senior credit facilities, additional amount allowed	250,000,000	250,000,000
Term loan, maximum facility	225,000,000	225,000,000
Term loan, amount outstanding	225,000,000	225,000,000	187,500,000
Term loans, periodic payment, principal	562,500
Line of credit, maximum facility	675,000,000	675,000,000
Line of credit, amount outstanding	100,000,000	100,000,000	160,500,000
Letters of credit outstanding, amount	104,700,000	104,700,000
Letters of credit, amount available	470,300,000	470,300,000
Unsecured line of credit, maximum facility	20,000,000	20,000,000
Unsecured line of credit, amount outstanding	$ 0	$ 0	$ 18,300,000
Eurodollar [Member]
Debt Instrument [Line Items]
Description of variable rate basis	Eurodollar rate
Alternate Base Rate [Member]
Debt Instrument [Line Items]
Description of variable rate basis	ABR rate
Revolving Facility [Member]
Debt Instrument [Line Items]
Maturity date	Mar. 19, 2019
Margin on Eurodollar rate, actual	2.25%	2.25%
Margin on ABR rate, actual	1.25%	1.25%
Revolving Facility [Member] | Eurodollar [Member] | Maximum [Member]
Debt Instrument [Line Items]
Basis margin on variable rate	2.75%
Revolving Facility [Member] | Eurodollar [Member] | Minimum [Member]
Debt Instrument [Line Items]
Basis margin on variable rate	1.50%
Revolving Facility [Member] | Alternate Base Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Basis margin on variable rate	1.75%
Revolving Facility [Member] | Alternate Base Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Basis margin on variable rate	0.50%
Term Loan [Member]
Debt Instrument [Line Items]
Maturity date	Mar. 19, 2021
Margin on Eurodollar rate, actual	3.00%	3.00%
Margin on ABR rate, actual	2.00%	2.00%