Principles of Consolidation - Additional Information (Detail) - Entity	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Number of securitization entities to which asset transferred	4	4	12

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_VariableInterestEntityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration