Goodwill and Other Intangible Assets - Details of Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Indefinite-lived Intangible Assets [Line Items]
Total intangible assets	$ 11,187	$ 4,900
Total accumulated amortization	(4,567)	(2,042)
Intangible assets, net	6,620	2,858
Domain Names [Member]
Indefinite-lived Intangible Assets [Line Items]
Total intangible assets	6,287
Total accumulated amortization	(75)
Customer Backlog [Member]
Indefinite-lived Intangible Assets [Line Items]
Total intangible assets	4,000	4,000
Total accumulated amortization	(3,667)	(1,666)
Trade Names and Trademarks [Member]
Indefinite-lived Intangible Assets [Line Items]
Total intangible assets	900	900
Total accumulated amortization	$ (825)	$ (376)