Subsequent Events - Additional Information (Detail) (VIE Primary Beneficiary [Member], Residual Trusts [Member], Subsequent Event [Member], USD $) In Millions, unless otherwise specified	0 Months Ended
Apr. 28, 2015	Apr. 27, 2015 Trust
VIE Primary Beneficiary [Member] \| Residual Trusts [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Number Of Securitization Trusts Related To Residual Trusts Sold		7
Proceeds from Sales of Assets, Investing Activities	$ 189.5

Aggregate cash proceeds received from a combination of transactions that are classified as investing activities in which assets, which may include one or more investments, are sold to third-party buyers. This element can be used by entities to aggregate proceeds from all asset sales that are classified as investing activities.

No definition available.

Name:	us-gaap_ProceedsFromSalesOfAssetsInvestingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration