Investments - Additional Information (Detail) $ in Thousands	9 Months Ended
Sep. 30, 2015 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Unrealized net (losses) gains on available-for-sale securities	$ 64
Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturity period of investments	One year or less

The change in unrealized holding gain (loss), net of tax, on available-for-sale securities included in a separate component of shareholders' equity during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563

Name:	us-gaap_AvailableForSaleSecuritiesChangeInNetUnrealizedHoldingGainLossNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration