Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
Jun. 30, 2013	Dec. 31, 2014	Dec. 31, 2013
Loans Receivable [Line Items]
Transfers out of Level 3	$ 300,000	$ 0	$ (344,000)
Liabilities measured at fair value on nonrecurring basis		$ 0

Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

No definition available.

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