Schedule of Outstanding Interest Rate Swaptions (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Weighted Average Remaining Term in Months	15 months
Options
Derivative [Line Items]
Original Cost	$ 4,000	$ 20,080
Fair Value	3,484	4,561
Weighted Average Remaining Term in Months	12 months	6 months
Underlying Swaps
Derivative [Line Items]
Notional Amount	$ 1,065,000	$ 992,300
Weighted Average Fixed Pay Rate	3.00%	2.74%
Receive Rate	3 month LIBOR	3 month LIBOR
Weighted Average Term (Years)	5 years	7 years