Supplemental Disclosures of Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Interest, net of capitalized interest	$ 12,602	$ 12,343
Income taxes	0	193
Change in accounts payable related to purchases of properties and equipment	14,941	51,093
Change in asset retirement obligation, with a corresponding change to crude oil and natural gas properties, net of disposals	2,794	5,354
Operating Lease, Payments	1,441	0
Finance Lease, Interest Payment on Liability	60	0
Finance Lease, Principal Payments	494	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	481	0
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 624	$ 0