Corporate Debt - Summary Components of Debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Unpaid principle balance	$ 2,352,131us-gaap_DebtInstrumentCarryingAmount
Other	2,131	4,106
Corporate debt	2,267,799	2,272,085
Term Loan [Member]
Debt Instrument [Line Items]
Amortized Cost	1,464,978	1,477,044
Unpaid principle balance	1,485,000	1,500,000
Weighted Average Stated Interest Rate	4.75%	4.75%
Senior Notes [Member]
Debt Instrument [Line Items]
Amortized Cost	575,000	575,000
Unpaid principle balance	575,000	575,000
Weighted Average Stated Interest Rate	7.875%	7.875%
Convertible Notes [Member]
Debt Instrument [Line Items]
Amortized Cost	225,690	215,935
Unpaid principle balance	$ 290,000	$ 290,000
Weighted Average Stated Interest Rate	4.50%	4.50%

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal, through the balance sheet date and due to be paid more than one year (or one operating cycle, if longer) after the balance sheet date.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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