Other Financial Information (Noncash Operating Working Capital (Increase) Decrease) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Net (increase) decrease in operating working capital other than cash and cash equivalents:
(Increase) decrease in accounts receivable	$ (141,793)	$ (26,533)
(Increase) decrease in inventories	(617)	21,683
(Increase) decrease in prepaid expenses	(12,190)	1,276
Increase (decrease) in accounts payable and accrued liabilities	147,569	26,673
Increase (decrease) in income taxes payable	1,665	(601)
Net (increase) decrease in noncash operating working capital	(5,366)	22,498	[1]
Supplementary disclosures:
Cash income taxes paid, net of refunds	79	(1,780)
Interest paid, net of amounts capitalized of $0 in 2019 and 2018	102,802	78,373
Amounts capitalized	0
Non-cash investing activities:
Asset retirement costs capitalized ¹	38,396	1,608
(Increase) decrease in capital expenditure accrual	$ (65,830)	$ 35,837

[1] Reclassified to conform to current presentation (See Note A).