Commitments - Additional Information (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2013
SecurityLoan
Purchase Commitment, Excluding Long-term Commitment [Line Items]  
Commitments to fund mortgage loans and other investments $ 6.6
Number of construction to permanent loan 1
Construction-to-Permanent Loan
 
Purchase Commitment, Excluding Long-term Commitment [Line Items]  
Commitments to fund mortgage loans and other investments 0.3
Real Estate Investments
 
Purchase Commitment, Excluding Long-term Commitment [Line Items]  
Commitments to fund mortgage loans and other investments 13.8
Subsequent event | Commercial Loan
 
Purchase Commitment, Excluding Long-term Commitment [Line Items]  
Commitments to fund mortgage loans and other investments $ 4.0