Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items]
Unrealized gains (losses) on securities recorded as other income	$ 27	$ (7)	$ 0	$ 0

Amount of unrealized gain (loss) recognized in the income statement on unsold other securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

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