Debt Obligations, net (Future Scheduled Maturities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Maturities of Long-term Debt [Abstract]
2015	$ 105,765
2016	926,403
2017	1,283,226
2018	615,239
2019	802,312
Thereafter	301,404
Total principal maturities	4,034,349us-gaap_DebtInstrumentCarryingAmount	4,196,589us-gaap_DebtInstrumentCarryingAmount
Unamortized debt discounts, net	(11,665)	(38,464)
Total long-term debt obligations, net	4,022,684us-gaap_LongTermDebt	4,158,125us-gaap_LongTermDebt
Unsecured Debt
Maturities of Long-term Debt [Abstract]
2015	105,765
2016	926,403
2017	924,722
2018	600,000
2019	770,000
Thereafter	100,000
Total principal maturities	3,426,890
Unamortized debt discounts, net	(8,371)
Total long-term debt obligations, net	3,418,519
Secured Debt
Maturities of Long-term Debt [Abstract]
2015	0
2016	0
2017	358,504
2018	15,239
2019	32,312
Thereafter	201,404
Total principal maturities	607,459
Unamortized debt discounts, net	(3,294)
Total long-term debt obligations, net	$ 604,165

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized.

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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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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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