Stockholders' Equity - Stock Repurchase Plan - Additional Information (Detail) - 2016 Stock Incentive Plan - USD ($)	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Feb. 29, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding common stock repurchase program authorized amount (up to)			$ 50,000,000.0
Shares repurchased during period	0	0
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 16,300,000

Number of shares that have been repurchased during the period and are being held in treasury.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration