Accumulated Other Comprehensive Income (Loss) - Schedule of Components of Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Other Comprehensive Income Loss Tax Parenthetical Disclosures [Abstract]
Tax on Unrealized [gain/loss] on investments before reclassification	$ 33	$ 29	$ 6
Tax on reclassification adjustment for net [gain/loss] realized in net income	$ (5)		$ (7)

Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e640-108580

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