Derivative Instruments and Hedging Activities - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative liabilities	$ 1,500	$ 1,463
Restricted cash and cash equivalents	20,800	54,200
Not Designated as Hedging Instrument | TBA
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative liabilities	228,000	283,500
Not Designated as Hedging Instrument | Interest Rate Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Restricted cash and cash equivalents	6,300	11,400
Cash Flow Hedging | Designated as Hedging Instrument | Interest Rate Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative in liability position	300	200
Derivative liability netted against asset position	$ 300	$ 1,300
Estimated time to transfer unrealized gains on interest rate swap from AOCI to income	12 months
Unrealized gains on interest rate swaps to be reclassified from AOCI to income	$ 300