Derivatives (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016		Mar. 31, 2015	Dec. 31, 2015
Derivative [Line Items]
Derivative assets, fair value					$ 7,835
Derivative assets, aggregate notional amount		$ 425,000			460,000
Derivative liabilities, fair value		(90,487)			(41,205)
Derivative liabilities, aggregate notional amount		8,005,000			9,220,000
Derivative assets		14,845			7,835
Derivative, Notional Amount		8,430,000			9,680,000
Loss on derivative instruments, net		(48,264)		$ (25,323)
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative assets, fair value		14,845			7,835
Derivative assets, aggregate notional amount		425,000			460,000
Derivative liabilities, fair value		(49,204)			(12,108)
Derivative liabilities, aggregate notional amount		1,705,000			2,920,000
Eurodollar Future [Member]
Derivative [Line Items]
Derivative assets, fair value		0			0
Derivative assets, aggregate notional amount		0	[1]		0
Derivative liabilities, fair value		(41,283)			(29,097)
Derivative liabilities, aggregate notional amount	[1]	6,300,000			6,300,000
Derivative, Notional Amount		6,300,000			6,300,000
Loss on derivative instruments, net		(12,186)		(16,488)
Receive-fixed interest rate swap [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount		425,000			425,000
Loss on derivative instruments, net		10,534		4,528
Pay-fixed interest rate swap [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount		1,705,000			$ 2,955,000
Loss on derivative instruments, net		$ (46,612)		$ (13,363)

[1] The Eurodollar futures aggregate notional amount represents the total notional of the 3-month contracts with expiration dates from 2017 to 2020. The maximum notional outstanding for any future 3-month period did not exceed $725,000 as of March 31, 2016