Debt Obligations, net (Future Scheduled Maturities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Maturities of Long-term Debt [Abstract]
2016	$ 926,403
2017	1,264,439
2018	863,290
2019	800,795
2020	0
Thereafter	295,462
Total principal maturities	4,150,389	$ 4,034,349
Debt discounts, net	(6,706)	(11,665)
Debt obligations, net	4,143,683	$ 4,022,684
Unsecured Debt
Maturities of Long-term Debt [Abstract]
2016	926,403
2017	924,722
2018	600,000
2019	770,000
2020	0
Thereafter	100,000
Total principal maturities	3,321,125
Debt discounts, net	(5,522)
Debt obligations, net	3,315,603
Secured Debt
Maturities of Long-term Debt [Abstract]
2016	0
2017	339,717
2018	263,290
2019	30,795
2020	0
Thereafter	195,462
Total principal maturities	829,264
Debt discounts, net	(1,184)
Debt obligations, net	$ 828,080

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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-Subparagraph (SX 210.5-02.22)
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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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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 in the next 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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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 in 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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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 in the fourth 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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