Other Financial Information (Noncash Opearting Working Capital Increase (Decrease)) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Other Financial Information [Abstract]
Decrease in accounts receivable	$ 90,614	$ 75,841
Decrease (increase) in inventories	5,869	(15,768)
Decrease in prepaid expenses	25,285	122,399
Decrease in other		720
Decrease in accounts payable and accrued liabilities	(115,977)	(376,310)	[1]
(Decrease) increase in current income tax liabilities	(4,721)	40,500
Net (increase) decrease in noncash operating working capital	1,070	(152,618)	[1]
Cash income taxes paid, net of refunds	25,118	(3,911)
Interest paid, net of amounts capitalized of $3,338 in 2017 and $3,318 in 2016	95,899	52,287
Asset retirement costs capitalized	38,992	13,959
Decrease in capital expenditure accrual	42,403	179,203
Payments for deepwater rig exit costs		266,600
Interest paid, amounts capitalized	$ 3,338	$ 3,318

[1] 2016 balance includes payments for deepwater rig contract exit of $266.6 million.