Leases - Schedule of Components of Lease Expense (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Lessee Lease Description [Line Items]
Operating lease cost	$ 3,080
Variable lease expense	1,151	[1]
Short-term lease expense / costs	92	[2]
Sublease income	(875)
Total lease expense	3,448
Natural Gas and Oil Properties
Lessee Lease Description [Line Items]
Short-term lease expense / costs	$ 9,164	[3]

[1] Variable lease payments that are not dependent on an index or rate are not included in the lease liability or ROU assets.

[2] Short-term lease expense represents expense related to leases with a contract term of one year or less.

[3] These short-term lease costs are related to leases with a contract term of one year or less and the majority of which are related to drilling rigs and are capitalized as part of natural gas and oil properties on our balance sheets