Summary of Significant Accounting Policies - Leases - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019
Operations And Summary Of Significant Accounting Policies [Line Items]
Operating Lease Right-of-Use Assets	$ 4,773
Operating lease liabilities, short term	2,007
Operating lease liabilities, long term	$ 2,766
Operating lease utilized discount rate	5.00%
Prior advance notice period for cancellation of rig contracts	30 days
Cash payments for operating leases associated with right-of-use assets	$ 502
Operating lease, weighted average remaining lease term	2 years 7 months 6 days
Operating lease, weighted average discount rate, percent	5.00%
Expected future payments for contracted drilling services	$ 17,000
Contract term related to drilling services	through October 2019
ASU 842
Operations And Summary Of Significant Accounting Policies [Line Items]
Operating Lease Right-of-Use Assets		$ 5,200
Operating lease liabilities, short term		2,000
Operating lease liabilities, long term		$ 3,200