Quantitative Information about Significant Unobservable Inputs Used in Valuation of Level 3 Assets and Liabilities Measured at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Residential Loans Priced To Securitization
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value, Assets	$ 230,465
Residential Loans Priced To Securitization | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	4.00%
Prepayment rate	15.00%
Default rate	1.00%
Loss severity	22.00%
Credit support	8.00%
Residential Loans Priced To Securitization | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	4.00%
Prepayment rate	15.00%
Default rate	1.00%
Loss severity	22.00%
Credit support	8.00%
Residential Loans Priced To Securitization | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	4.00%
Prepayment rate	15.00%
Default rate	1.00%
Loss severity	22.00%
Credit support	8.00%
Residential Loans Priced To Whole Loan Market and Committed to Sell
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value, Assets	401,009
Residential Loans Priced To Whole Loan Market and Committed to Sell | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Pool fallout assumption	0.00%
Residential Loans Priced To Whole Loan Market and Committed to Sell | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Pool fallout assumption	0.00%
Residential Loans Priced To Whole Loan Market and Committed to Sell | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Pool fallout assumption	0.00%
Residential Loans Priced To Whole Loan Market And Uncommitted To Sell
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value, Assets	94,688
Residential Loans Priced To Whole Loan Market And Uncommitted To Sell | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Base Price	101.50%
Base Coupon	3.20%
Buy up (x coupon difference from base coupon)	2
Buy Down (x coupon difference from base coupon)	3
Residential Loans Priced To Whole Loan Market And Uncommitted To Sell | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Base Price	101.50%
Base Coupon	4.10%
Buy up (x coupon difference from base coupon)	2
Buy Down (x coupon difference from base coupon)	3
Residential Loans Priced To Whole Loan Market And Uncommitted To Sell | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Base Price	101.50%
Base Coupon	3.90%
Buy up (x coupon difference from base coupon)	2
Buy Down (x coupon difference from base coupon)	3
Residential Loans at Lower of Cost or Fair Value
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value, Assets	1,116
Residential Loans at Lower of Cost or Fair Value | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	15.00%
Residential Loans at Lower of Cost or Fair Value | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	28.00%
Residential Loans at Lower of Cost or Fair Value | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	21.00%
Commercial Loans Held For Sale
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value, Assets	27,413
Commercial Loans Held For Sale | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit Spread	1.61%
Credit support	20.00%
Commercial Loans Held For Sale | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit Spread	1.61%
Credit support	20.00%
Commercial Loans Held For Sale | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit Spread	1.61%
Credit support	20.00%
Trading and AFS securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value, Assets	1,324,678
Trading and AFS securities | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	5.00%
Prepayment rate	1.00%
Default rate	0.00%
Loss severity	20.00%
Credit support	0.00%
Trading and AFS securities | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	13.00%
Prepayment rate	40.00%
Default rate	35.00%
Loss severity	66.00%
Credit support	61.00%
Trading and AFS securities | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	7.00%
Prepayment rate	13.00%
Default rate	8.00%
Loss severity	32.00%
Credit support	5.00%
Mortgage Servicing Rights
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value, Assets	60,234
Mortgage Servicing Rights | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	9.00%
Prepayment rate	6.00%
Mortgage Servicing Rights | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	11.00%
Prepayment rate	60.00%
Mortgage Servicing Rights | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	11.00%
Prepayment rate	9.00%
REO
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value, Assets	$ 1,305
REO | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Historical loss adjustment	0.00%
REO | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Historical loss adjustment	40.00%
REO | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Historical loss adjustment	15.00%