Supplemental Cash Flow Information (Details) - USD ($) shares in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Supplemental Cash Flow Elements [Line Items]
Interest, net of capitalized interest	$ 51,556,000	$ 41,483,000
Income taxes	(204,000)	261,000
Capital Expenditures Incurred but Not yet Paid	(31,403,000)	(32,943,000)
Increase (Decrease) in Asset Retirement Obligations	44,339,000	13,493,000
Change in accounts payable related to the purchase and retirement of treasury shares [Line Items]	$ 0	$ 2,818,000
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued	1,009,015	0
Operating Lease, Payments	$ 6,714,000	$ 4,107,000
Operating Cash Flow from Financing Leases	155,000	193,000
Finance Lease, Principal Payments	1,454,000	1,492,000
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	4,217,000	1,428,000
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 703,000	$ 2,323,000