Variable Interest Entities - VIE Income Statement (Details) - Variable Interest Entity Primary Beneficiary [Member]	12 Months Ended
	Dec. 31, 2014 USD ($)
Portfolio Income [Abstract]
Interest income	$ 31,804,000
Interest expense	3,031,000
Net interest income	28,773,000
Unrealized gains on mortgage-backed securities	11,368,000
Realized gains on mortgage-backed securities	2,791,000
Losses on derivative financial instruments	(13,925,000)
Net portfolio income	29,007,000
Selling General And Administrative Expense [Abstract]
Accrued Incentive Compensation	500,000
Directors' fees and liability insurance	569,000
Audit, legal and other professional fees	588,000
Direct REIT operating expenses	182,000
Other administrative	246,000
Total expenses	2,085,000
Net income	$ 26,922,000