Mortgage-Backed Securities - Additional Information (Details)	3 Months Ended
Mar. 31, 2014
Minimum
Investments Classified By Contractual Maturity Date [Line Items]
Contractual maturity of Company's agency securities, in years	15 years
Maximum
Investments Classified By Contractual Maturity Date [Line Items]
Contractual maturity of Company's agency securities, in years	30 years

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration