Other Financial Information (Noncash Operating Working Capital (Increase) Decrease) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Other Financial Information [Abstract]
Capitalized interest paid	$ 2,400	$ 0
Net (increase) decrease in operating working capital, excluding cash and cash equivalents:
(Increase) decrease in accounts receivable	186,436	(112,673)
(Increase) decrease in inventories	7,553	3,930
(Increase) decrease in prepaid expenses	(10,179)	(10,763)
Increase (decrease) in accounts payable and accrued liabilities	(76,287)	21,131
Increase (decrease) in income taxes payable	304	(130)
Net (increase) decrease in noncash operating working capital	107,827	(98,505)
Supplementary disclosures:
Cash income taxes paid, net of refunds	72	0
Interest paid, net of amounts capitalized of $2.4 million in 2020 and $0 million in 2019	42,344	39,024
Non-cash investing activities:
Asset retirement costs capitalized	280	486
(Increase) decrease in capital expenditure accrual	$ 10,633	$ (63,328)