Assets Held for Sale and Discontinued Operations (Major Categories of Assets and Liabilities Reflected as Held for Sale) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current liabilities
Total current liabilities associated with assets held for sale	$ 14,097	$ 14,372
Discontinued Operations, Held-for-sale or Disposed of by Sale | Brunei Exploration And Production Operations
Current assets
Cash	9,469	10,185
Inventories	193	406
Property, plant, and equipment, net	58,294	307,704
Deferred income taxes and other assets	9,441	9,441
Total current assets associated with assets held for sale	77,397	327,736
Current liabilities
Accounts payable	5,213	5,306
Other accrued liabilities	36	45
Current maturities of long-term debt (finance lease)	746	737
Taxes payable	1,510	1,510
Long-term debt (finance lease)	6,325	6,513
Asset retirement obligation	267	261
Total current liabilities associated with assets held for sale	$ 14,097	$ 14,372