Senior Debt (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
Senior Debt (Details) [Abstract]
Borrowing in Term Loans	$ 225,000,000
Borrowing in Revolving Debt	100,000,000
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	223,900,000	223,900,000	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	195,000,000	195,000,000	160,500,000
Letters of credit outstanding, amount	104,700,000	104,700,000
Letters of credit, amount available	375,300,000	375,300,000
Unsecured line of credit, maximum facility	20,000,000	20,000,000
Unsecured line of credit, amount outstanding	6,300,000	6,300,000	18,300,000
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	0.50%
Financial Covenants Ratios (Table Details) [Abstract]
Required consolidated total leverage ratio, maximum	4.50	4.50
Actual consolidated total leverage ratio	3.43	3.43
Required consolidated senior secured leverage ratio, maximum	2.75	2.75
Actual consolidated senior secured leverage ratio	1.4	1.4
Required consolidated fixed charge coverage ratio, minimum	1.5	1.5
Actual consolidated fixed charge coverage ratio	1.78	1.78
Covenants [Abstract]
Outstanding indebtedness less cash in excess of	25,000,000	25,000,000
Consolidated funded debt outstanding	938,200,000	938,200,000
Consolidated EBITDA		273,200,000
Consolidated senior secured debt outstanding	381,900,000	381,900,000
Adjusted consolidated EBITDA		519,000,000
Consolidated fixed charges		$ 290,900,000
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	2.50%	2.50%
Margin on ABR rate, actual	1.50%	1.50%
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%