Other Non-Current Obligations - Schedule of Other Non-Current Obligations (Parenthetical) (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Aug. 04, 2018	May 05, 2018	Aug. 04, 2018
Other Non Current Obligations [Line Items]
Incentive payment service agreement period			5 years
Loss on extinguishment of debt		$ 917		$ 917
Equipment Security Notes [Member]
Other Non Current Obligations [Line Items]
Loss on extinguishment of debt	$ 200
Promissory Note [Member]
Other Non Current Obligations [Line Items]
Loss on extinguishment of debt	$ 200