Other Financial Information (Noncash Opearting Working Capital Increase (Decrease)) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Other Financial Information [Abstract]
Decrease in accounts receivable		$ 36,246	$ 2,354
Decrease in inventories		4,497	1,667
Decrease in prepaid expenses		17,788	98,888
Decrease in other			6,134
Decrease in accounts payable and accrued liabilities		(44,240)	(225,309)	[1]
Increase in current income tax liabilities		29,127	11,919
Net (increase) decrease in noncash operating working capital	[1]	43,418	(104,347)
Cash income taxes paid, net of refunds		3,422	(7,865)
Interest paid, net of amounts capitalized		17,720	1,849
Asset retirement costs capitalized		565	3,723
Decrease in capital expenditure accrual		12,906	81,858
Payments for deepwater rig exit costs		$ 253,200	$ 253,200

[1] 2016 balance includes payments for deepwater rig contract exit of $253.2 million.