Cash Flow Disclosures (Cash Flow Activities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015
Cash Flow Disclosures [Abstract]
Accounts receivable	$ 2,354		$ 302,602
Inventories	1,667		(60,562)
Prepaid expenses	98,888		(6,825)
Deferred income tax assets	6,134		5,040
Accounts payable and accrued liabilities	(225,309)		(17,281)
Current income tax liabilities	11,919		35,833
Net (increase) decrease in noncash operating working capital	(104,347)	[1]	258,807
Cash income taxes paid, net of refunds	(7,865)		28,280
Interest paid, net of amounts capitalized	1,849		(64)
Asset retirement costs capitalized	3,723		6,380
Decrease in capital expenditure accrual	$ 81,858		$ 239,572

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