Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017		Sep. 30, 2017		Jan. 01, 2017
ASU 2017-04
Significant Accounting Policies [Line Items]
Goodwill impairment charge			$ 0
ASU 2016-09
Significant Accounting Policies [Line Items]
Recognized excess tax benefits from stock-based compensation	$ 2,200,000		5,700,000
Cumulative-effect adjustment for previously unrecognized excess tax benefits	$ 2,650,000	[1]	$ 2,650,000	[1]	$ 2,700,000

[1] See Note 2, Significant Accounting Policies, for additional details related to the impact of the adoption of ASU 2016-09 during the nine months ended September 30, 2017.