Variable Interest Entities - Additional Information (Detail) (USD $)	12 Months Ended		0 Months Ended
	Dec. 31, 2014 Trust	Dec. 31, 2013 Trust	Jul. 02, 2014	Jul. 01, 2014	Nov. 30, 2014
Variable Interest Entity [Line Items]
Mandatory Cleanup Calls Must Be Performed On Non Residual Trusts When Each Loan Pool Falls To Percent Of Original Principal Balance	10.00%
Principal Amount Outstanding on Loans Securitized or Asset-backed Financing Arrangement	$ 173,800,000	197,300,000
VIE Primary Beneficiary [Member] | Residual Trusts [Member]
Variable Interest Entity [Line Items]
Number Of Securitization Trusts Related To Residual Trusts	12
VIE Primary Beneficiary [Member] | Non Residual Trusts [Member]
Variable Interest Entity [Line Items]
Expected Period To Exercise Mandatory Clean Up Call Obligation	2017 and continuing through 2019
Outstanding Balance Of Collateral For Mandatory Clean Up Call Obligation	417,200,000
Number Of Securitization Trusts Consolidated And Not Consolidated With Reimbursement Obligations	7
Number Of Securitization Trusts Related To Non Residual Trusts	10
Variable Interest Entities Primary Beneficiary And Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Aggregate Number Of Securitization Trusts Consolidated And Not Consolidated With Reimbursement Obligations	11
Reimbursement Obligation of LOC, If Drawn	165,000,000.0
Amount Of Loc Available For Eleven Securitization Trusts	265,200,000	273,600,000
Variable Interest Entity, Not Primary Beneficiary [Member] | Servicing Arrangements With Letter Of Credit Reimbursement Obligation [Member]
Variable Interest Entity [Line Items]
Number Of Securitization Trusts Consolidated And Not Consolidated With Reimbursement Obligations	4	4
Variable Interest Entity, Not Primary Beneficiary [Member] | WCO [Member]
Variable Interest Entity [Line Items]
Equity Interest Percentage	100.00%
Capital Commitment				20,000,000
Capital Contribution			7,100,000
Investment Advisory, Management and Administrative Fees	300,000
York [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | WCO [Member]
Variable Interest Entity [Line Items]
Capital Commitment				200,000,000
Secured Debt [Member]
Variable Interest Entity [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,500,000,000
Secured Debt [Member] | Servicer Advance Facility [Member]
Variable Interest Entity [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,200,000,000.0				$ 100,000,000