Supplemental Disclosures of Cash Flow Information - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Cash paid for interest	$ 55,470	$ 50,063	$ 61,295
Cash paid for income taxes	0	0	0
Cash paid for operating leases	1,315
Operating leases	14,999
Supplemental disclosures of non-cash investing and financing activities:
Accrued liabilities - oil and gas properties	28,130	98,346	43,980
Change in asset retirement obligations, net of disposals	(5,538)	10,778	5,376
Fair value of debt exchanged for common stock	0	0	48,992
Retirement of treasury stock	(1,729)	(1,535)	(1,253)
Properties exchanged in non-cash transactions	4,561	0	13,323
Issuance of common stock for Merger	$ 0	$ 484,000	$ 0