Fair Value (Schedule of Financial Instruments Utilizing Level 3 Inputs) (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 100,911,651	$ 76,473,092
Total net transfers into/out of Level 3
Acquisitions	193,538,950	68,617,460
Proceeds from sales		(43,379,205)
Net accretion of discounts	6,706,957	1,337,369
Proceeds from principal repayments	(24,322,480)	(16,938,626)
Total losses (realized / unrealized) included in earnings	(7,505,685)	(2,579,401)
Total gains (realized / unrealized) included in earnings	705,197	17,380,962
Ending balance	270,034,590	100,911,651
The amount of total gains or (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held at the reporting date	(14,228,335)	10,764,268
Mortgage Receivables Member
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance
Total net transfers into/out of Level 3
Acquisitions	119,758,049
Proceeds from sales
Net accretion of discounts	259,435
Proceeds from principal repayments	(867,594)
Total losses (realized / unrealized) included in earnings
Total gains (realized / unrealized) included in earnings	1,633,535
Ending balance	120,783,425
The amount of total gains or (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held at the reporting date	$ 1,567,291