Cash Flow Disclosures (Cash Flow Activities) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash Flow Disclosures [Abstract]
Decrease in accounts receivable	$ 389,413	$ 29,586
Increase in inventories	(16,607)	(3,326)
Increase in prepaid expenses	(87,051)	(2,235)
Decrease in deferred income tax assets	4,863	1,290
Increase (decrease) in accounts payable and accrued liabilities	(134,458)	59,369
Decrease in current income tax liabilities	(59,134)	(77,744)
Total	97,026	6,940
Cash income taxes paid, net of refunds	111,897	438,309
Interest paid, net of amounts capitalized	60,766	44,657
Asset retirement costs capitalized	55,258	15,509
Decrease in capital expenditure accrual	$ 374,720	$ 106,031