Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	9 Months Ended
Sep. 30, 2017 USD ($)
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Excess tax benefit from share-based compensation	$ 2,229
Accounting Standards Update 2016-09 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Excess tax benefit from share-based compensation	$ 2,200

Amount of cash outflow for realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 20
-Section 55
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=96864182&loc=d3e11374-113907

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