Commitments and Contingencies - Additional Information (Detail) - Ambac Assurance [Member] $ in Thousands	6 Months Ended
Jun. 30, 2016 USD ($)
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	$ 285,000
Litigation settlement amount	$ 4,733

The amount or range of possible amounts of gain that could be realized upon the resolution of a contingency.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355

Name:	us-gaap_GainContingencyUnrecordedAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant