Mortgage-Backed Securities - By Maturity (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Mortgage Backed Securities [Abstract]
Greater than five years and less than ten years	$ 1,134,000	$ 1,521,000
Greater than or equal to ten years	874,870,000	349,702,000
Total mortgage-backed securities	$ 876,004,251	$ 351,222,512