Revenue from Contracts with Customers - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Percentage of primary source of revenue	89.50%	88.90%	89.80%	88.80%