Derivative Instruments (Schedule of Losses and Gains of Derivative Instruments) (Details) (Not Designated as Hedging Instrument [Member], USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative instruments	$ 8,272,229		$ (897,767)		$ 8,216,927		$ (755,952)
TBAs [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative instruments	(4,573,848)	[1]		[1]	(4,237,402)	[1]		[1]
Realized gains (losses) on sale of derivative					800,000
Unrealized gains (losses) recognized					$ (5,400,000)

[1] Gains and losses from purchases and sales of TBAs consists of $0.8 million of net TBA dollar roll net interest income and a net loss of $5.4 million due to price declines.