Residential Loans - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014 Contract CreditScore	Dec. 31, 2013 Contract	Dec. 31, 2012
Mortgage Loans on Real Estate [Line Items]
Carrying value	$ 3,398,573,000	$ 2,166,434,000	$ 2,835,470,000
Residential Loans Held for Investment
Mortgage Loans on Real Estate [Line Items]
Carrying value	1,474,386,000	1,762,167,000
Number of Loans	5,315	6,206
Principal value	1,483,213,000	1,770,803,000
Unamortized premium, net	13,000,000	17,000,000
Weighted average original loan-to-value (LTV)	66.00%
Weighted average original Fair Isaac Corporation (FICO) score	733
Charge-offs, net	5,000,000	5,000,000	12,000,000
Principal value	21,000,000	14,000,000	33,000,000
Residential Loans Held for Investment \| Residential Loans Acquired Prior To July 1st 2004
Mortgage Loans on Real Estate [Line Items]
Principal value	598,000,000	731,000,000
Unamortized premium, net	8,000,000	11,000,000
Percentage of loans prepaid	18.00%
Percentage of premiums amortized	30.00%
Residential Loans Held for Investment \| Residential Loans Acquired After July 1st 2004
Mortgage Loans on Real Estate [Line Items]
Principal value	889,000,000	1,040,000,000
Unamortized premium, net	5,000,000	6,000,000
Percentage of loans prepaid	15.00%
Percentage of premiums amortized	18.00%
Residential Loans Held for Investment \| First Mortgage
Mortgage Loans on Real Estate [Line Items]
Percentage of loan portfolio	99.00%
Residential Loans Held for Investment \| Second Mortgage
Mortgage Loans on Real Estate [Line Items]
Percentage of loan portfolio	1.00%
Residential Loans
Mortgage Loans on Real Estate [Line Items]
Principal value	8,810,000,000	7,010,000,000
Charge-offs, net	4,966,000	4,525,000	11,903,000
Loss confirmation period	23 months
Average recorded investment of loans individually evaluated for impairment	13,000,000	7,000,000	14,000,000
Interest income recognized on impaired loans	129,000	123,000	297,000
Residential Loans at Fair Value
Mortgage Loans on Real Estate [Line Items]
Carrying value	1,340,000,000	403,000,000
Number of Loans	2,273	537
Principal value	1,300,000,000	399,000,000
Negative Valuation adjustments	51,256,000	(10,493,000)	37,762,000
Residential Loans at Lower of Cost or Fair Value
Mortgage Loans on Real Estate [Line Items]
Carrying value	1,488,000	1,665,000
Number of Loans	9	10
Principal value	2,000,000	2,000,000
Valuation adjustments	56,000	38,000
Residential Loans at Lower of Cost or Fair Value \| Carrying Value
Mortgage Loans on Real Estate [Line Items]
Carrying value	2,000	2,000
Residential Loans Held For Investment at Fair Value
Mortgage Loans on Real Estate [Line Items]
Carrying value	581,668,000
Number of Loans	804
Principal value	566,372,000
Principal balance of loans transferred	574,000,000
Fair value of loans transferred	564,000,000
Residential Loans Held For Sale
Mortgage Loans on Real Estate [Line Items]
Carrying value	1,342,519,000	404,267,000
Number of Loans	2,282	547
Principal value	1,305,493,000	400,873,000
Residential Loans Held For Sale \| Mortgage Servicing Rights
Mortgage Loans on Real Estate [Line Items]
Carrying value	$ 1,700,000,000

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Fair Value Of Loans Securitized During Period

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Loan To Value Ratio

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Loss Confirmation Period

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Percentage Of Loan Portfolio

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Percentage Of Loan Premiums Amortized

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Percentage Of Loans Prepaid

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Principal Amount Of Loans Securitized During Period

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Principal Balance of Loans Acquired During Period

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The weighted average FICO score for borrowers at the time loans were originated.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of consumer loans, including, but not limited to, mortgage, home equity, vehicles, credit card, installment, and lease financing. Excludes loans and leases covered under loss sharing agreements.

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Indicates the number of mortgages under each classification.

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The total periodic movement (increases and decreases) in the carrying amount of mortgage loans on real estate.

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This is the sum of principal amount outstanding for both securitized and unsecuritized loans of all types.

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Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

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