Mortgage-Backed Securities - By Type (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Mortgage Backed Securities [Line Items]
Fair Value	$ 380,559,808	$ 168,155,007
[VariableInterestEntityPrimaryBeneficiaryMember]
Mortgage Backed Securities [Line Items]
Fair Value	339,147,913	0
[MortgageBackedSecuritiesPassThroughCertificatesMember]
Mortgage Backed Securities [Line Items]
Fair Value	356,071,000	158,396,000
[MortgageBackedSecuritiesStructuredCertificatesMember]
Mortgage Backed Securities [Line Items]
Fair Value	24,489,000	9,759,000
[HybridAdjustableRateMortgagesMember] | [MortgageBackedSecuritiesPassThroughCertificatesMember]
Mortgage Backed Securities [Line Items]
Fair Value	116,618,000	87,693,000
[AdjustableRateMortgagesMember] | [MortgageBackedSecuritiesPassThroughCertificatesMember]
Mortgage Backed Securities [Line Items]
Fair Value	6,210,000	20,857,000
[FixedRateMortgagesMember] | [MortgageBackedSecuritiesPassThroughCertificatesMember]
Mortgage Backed Securities [Line Items]
Fair Value	233,243,000	49,846,000
[InterestOnlySecuritiesMember] | [MortgageBackedSecuritiesStructuredCertificatesMember]
Mortgage Backed Securities [Line Items]
Fair Value	21,907,000	5,244,000
[InverseInterestOnlyMember] | [MortgageBackedSecuritiesStructuredCertificatesMember]
Mortgage Backed Securities [Line Items]
Fair Value	$ 2,582,000	$ 4,515,000