Cash Flow Disclosures (Cash Flow Activities) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016		Sep. 30, 2015
Cash Flow Disclosures [Abstract]
Decrease in accounts receivable	$ 75,841		$ 389,413
Increase in inventories	(15,768)		(16,607)
Decrease (increase) in prepaid expenses	122,399		(87,051)
Decrease in deferred income tax assets	720		4,863
Decrease accounts payable and accrued liabilities	(376,310)		(134,458)
Increase (decrease) in current income tax liabilities	40,500		(59,134)
Net (increase) decrease in noncash operating working capital	(152,618)	[1]	97,026
Cash income taxes paid (refunded), net	(3,911)		111,897
Interest paid, net of amounts capitalized	52,287		60,766
Asset retirement costs capitalized	13,959		55,258
Decrease in capital expenditure accrual	$ 179,203		$ 374,720

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