Cash Flow Disclosures (Cash Flow Activities) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016		Jun. 30, 2015
Cash Flow Disclosures [Abstract]
Decrease in accounts receivable	$ 109,105		$ 284,542
Increase in inventories	(4,659)		(25,547)
Decrease (increase) in prepaid expenses	99,524		(40,191)
Decrease in deferred income tax assets	5,564		5,092
Decrease accounts payable and accrued liabilities	(337,302)		(84,781)
Increase (decrease) in current income tax liabilities	40,975		(31,944)
Net (increase) decrease in noncash operating working capital	(86,793)	[1]	107,171
Cash income taxes paid (refunded), net	(4,367)		90,419
Interest paid, net of amounts capitalized	52,654		55,658
Asset retirement costs capitalized	8,693		6,703
Decrease in capital expenditure accrual	$ 165,329		$ 336,952

[1] 2016 balance includes payments for deepwater rig contract exit of $261.8 million.