Supplemental Disclosures of Cash Flow Information - Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Supplemental Cash Flow Information [Abstract]
Cash paid for interest	$ 868	$ 395
Cash paid for income taxes	0	0
Operating cash flows from operating leases	229	0
Operating leases (1)	14,667	0
Non-cash investing and financing activities:
Accrued liabilities - oil and gas properties	92,702	67,047
Change in asset retirement obligations, net of disposals	933	7,513
Retirement of treasury stock	(1,484)	(1,462)
Issuance of common stock for Merger	$ 0	$ 484,000