Property and Equipment, Net - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Property and Equipment [Line Items]
Computer software development costs capitalized	$ 4,600,000	$ 3,500,000	$ 11,200,000	$ 6,400,000
Retainage amount included in construction in progress					$ 2,000,000
Interest cost Paid	400,000	400,000	800,000	800,000
Interest Costs Capitalized	300,000	100,000	700,000	200,000
Depreciation and amortization	3,459,000	2,440,000	6,491,000	4,666,000
Property and Equipment [Member]
Property and Equipment [Line Items]
Depreciation and amortization	6,700,000	$ 4,300,000	12,700,000	$ 8,200,000
Maximum [Member]
Property and Equipment [Line Items]
Retainage amount included in construction in progress	$ 100,000		$ 100,000