Fair Values of Financial Instruments - Summary of Changes in Fair Value of Assets Measured at Fair Value (Detail) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Fair Value Measurements Disclosure [Line Items]
Balance at beginning of year	$ 11,748	$ 10,591
Total unrealized gains	469	1,157
Balance at end of year	$ 12,217	$ 11,748

Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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