Goodwill and Other Intangible Assets - Summary of Other Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Summary Of Other Intangible Assets [Line Items]
Gross carrying amount	$ 29,706	$ 22,043
Accumulated amortization	14,327	10,875
Net carrying amount	15,379	11,168
Gross carrying amount	27,525	20,218
Accumulated amortization	14,327	10,875
Net carrying amount	$ 13,198	$ 9,343
Developed Technology [Member]
Summary Of Other Intangible Assets [Line Items]
Weighted-average useful life of acquired finite-lived intangible assets	4 years	4 years
Gross carrying amount	$ 17,347	$ 10,631
Accumulated amortization	7,642	5,034
Net carrying amount	$ 9,705	$ 5,597
Customer Relationships [Member]
Summary Of Other Intangible Assets [Line Items]
Weighted-average useful life of acquired finite-lived intangible assets	7 years	7 years
Gross carrying amount	$ 9,235	$ 8,646
Accumulated amortization	5,816	4,977
Net carrying amount	$ 3,419	$ 3,669
Noncompete Agreements [Member]
Summary Of Other Intangible Assets [Line Items]
Weighted-average useful life of acquired finite-lived intangible assets	5 years	5 years
Gross carrying amount	$ 824	$ 824
Accumulated amortization	$ 824	$ 824
Other Intangibles [Member]
Summary Of Other Intangible Assets [Line Items]
Weighted-average useful life of acquired finite-lived intangible assets	10 years	10 years
Gross carrying amount	$ 119	$ 117
Accumulated amortization	45	40
Net carrying amount	74	77
Trade Names [Member]
Summary Of Other Intangible Assets [Line Items]
Net carrying amount	$ 2,181	$ 1,825