Schedule of ARM Securities Forward Purchase Commitments (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Forward purchase agreements - Face	$ 105,239	$ 0
Forward purchase agreements - Cost	107,814	0
Forward purchase agreements - Fair Value	107,798	0
Forward purchase agreements - Net Asset (Liability)	$ (16)	$ 0