Commercial Loans - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commercial Loans [Line Items]
Carrying Value	$ 566,927,000	$ 432,455,000	$ 313,010,000
Senior commercial loans, held for sale	9,917,943,000	7,766,203,000	2,335,865,000
Sale of loan for third party, held for sale	8,126,249,000	7,405,088,000	1,696,433,000
Commercial Loans Held For Investment
Commercial Loans [Line Items]
Commercial loans financed through Commercial Securitization entity	195,000,000	258,000,000
Number of Loans	60	50
Principal value	341,750,000	353,331,000
Carrying Value	400,693,000	343,344,000
Commercial Loans Held For Sale
Commercial Loans [Line Items]
Number of Loans	13
Principal value	163,000,000
Carrying Value	166,234,000	89,111,000
Senior commercial loans, held for sale	904,000,000
Sale of loan for third party, held for sale	791,000,000
Valuation adjustments	21,000,000
Commercial Loans Held For Sale \| Maximum
Commercial Loans [Line Items]
Valuation adjustments			1,000,000
Commercial Loans at Fair Value
Commercial Loans [Line Items]
Number of Loans		7
Principal value		88,000,000
Carrying Value	166,234,000	89,111,000
Senior commercial loans, held for sale		659,000,000
Sale of loan for third party, held for sale		597,000,000
Valuation adjustments		9,000,000
Commercial Loans Held-for-Investment, at Fair Value
Commercial Loans [Line Items]
Number of Loans	3
Principal value	68,000,000
Carrying Value	71,262,000
Senior commercial loans, held for sale	31,000,000
Valuation adjustments	2,000,000
Commercial Loans Held-for-Investment, at Amortized Cost
Commercial Loans [Line Items]
Commercial loans financed through Commercial Securitization entity	195,000,000
Number of Loans	60	50
Carrying Value	329,431,000	343,344,000
Principal balance	341,750,000	353,331,000
Senior commercial loans, held for Investment	59,000,000	66,000,000
Recorded investment	336,888,000	350,717,000
Loan prepayment amount received	71,000,000	24,000,000
Loan prepayments, yield maintenance fee	$ 1,500,000	$ 3,000,000
Commercial Loans Held-for-Investment, at Amortized Cost \| Originated During 2014
Commercial Loans [Line Items]
Percentage of loan portfolio	17.00%
Commercial Loans Held-for-Investment, at Amortized Cost \| Originated During 2013
Commercial Loans [Line Items]
Percentage of loan portfolio	17.00%	19.00%
Commercial Loans Held-for-Investment, at Amortized Cost \| Originated During 2012
Commercial Loans [Line Items]
Percentage of loan portfolio	36.00%	43.00%
Commercial Loans Held-for-Investment, at Amortized Cost \| Originated During 2011
Commercial Loans [Line Items]
Percentage of loan portfolio	26.00%	34.00%
Commercial Loans Held-for-Investment, at Amortized Cost \| Originated During 2010
Commercial Loans [Line Items]
Percentage of loan portfolio	4.00%	4.00%

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Loans and Leases Receivable, Prepayment Amount Received

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Loans and Leases Receivable, Yield Maintenance Fees Received

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- Definition

Loans Financed through Securitization

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- Definition

Percentage Of Loan Portfolio

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- Definition

Reflects the aggregate gross carrying amount of all commercial loans and leases held in portfolio, prior to deducting deferred income and the allowance for losses on commercial loans and leases.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of commercial loans and leases receivable including, but not limited to, commercial and industrial loans, agricultural loans, mortgage loans, promissory notes, interbank and other loans to financial institutions, draws against credit facilities, trade financing, lease financings. 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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Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

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The cash outflow associated with purchasing loans held for investment purposes during the period.

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The aggregate cash outflow used to purchase all loans that are held with the intention to resell in the near future.

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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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The cash inflow resulting from the sale of loans classified as held-for-sale, including proceeds from loans sold through mortgage securitization.

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