Derivative Instruments and Hedging Activities - Interest Rate Swaps (Details) - Cash Flow Hedging - Designated as Hedging Instrument - Interest rate swaps - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	$ 225,000	$ 225,000
Weighted Average Fixed Interest Rate	0.90%	0.90%
Weighted Average Variable Interest Rate	0.44%	0.40%
2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	$ 215,000	$ 215,000
Weighted Average Fixed Interest Rate	0.83%	0.83%
Weighted Average Variable Interest Rate	0.43%	0.39%
2019
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	$ 10,000	$ 10,000
Weighted Average Fixed Interest Rate	2.25%	2.25%
Weighted Average Variable Interest Rate	0.64%	0.59%
Agency IOs
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	$ 5,000	$ 0
Weighted Average Fixed Interest Rate	1.80%	0.00%
Weighted Average Variable Interest Rate	0.62%	0.00%
Agency IOs | 2026
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	$ 5,000	$ 0
Weighted Average Fixed Interest Rate	1.80%	0.00%
Weighted Average Variable Interest Rate	0.62%	0.00%