Commitments and Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	0 Months Ended	9 Months Ended
Dec. 06, 2013 petition	Sep. 30, 2014
Loss Contingencies [Line Items]
Number of petitions filed	2
Litigation Settlement, Amount		$ 7,760
Ambac Assurance [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Expense		$ 207

Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

No definition available.

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