Fair Value of Financial Instruments - Additional Information (Detail)	Jun. 30, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Dealer marks of securities	83.00%
Percentage difference of internal valuation than dealer marks	(3.00%)
Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Dealer marks of securities	95.00%
Percentage difference of internal valuation than dealer marks	7.00%