Related Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Former Chairman, President and Chief Executive Officer [Member]
Related Party Transaction [Line Items]
Flight charter services fees		$ 0.2
Maximum [Member] | Former Chairman, President and Chief Executive Officer [Member]
Related Party Transaction [Line Items]
Flight charter services fees	$ 0.1
EnCap and Affiliates [Member] | Montage Resources Corporation [Member]
Related Party Transaction [Line Items]
Percentage of ownership interest	40.00%