Supplemental Cash Flow Information (Details) - USD ($) shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Supplemental Cash Flow Elements [Line Items]
Interest, net of capitalized interest	$ 30,855	$ 39,168
Income taxes	(1,125)	(204)
Change in accounts payable related to capital expenditures	61,310	(7,223)
Asset Retirement Obligation, Period Increase (Decrease)	$ (1,729)	$ 44,082
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued	0	1,009,015
Operating Lease, Payments	$ 4,054	$ 4,421
Operating Cash Flow from Financing Leases	65	109
Finance Lease, Principal Payments	879	985
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	1,066	4,217
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 1,466	$ 703