Income Taxes (Effective Income Tax Rates) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income tax expense (benefit) based on the U.S. statutory tax rate	$ (172,590)	$ (1,148,792)	$ 438,295
Foreign income (loss) subject to foreign tax rates different than the U.S. statutory rate	8,582	49,739	20,562
State income taxes, net of federal benefit	9,090	(3,441)	5,746
U.S. tax benefit on certain foreign upstream investments	(21,336)	(16,939)	(95,838)
Current tax in distribution of foreign earnings			52,724
Deferred tax on distribution of foreign earnings		188,461
Increase in deferred tax asset valuation allowance related to other foreign exploration expenditures	25,734	40,788	37,712
Other, net	18,741	(13,747)	(4,663)
Total income tax expense (benefit)	(219,172)	(1,026,490)	227,297
Canada [Member]
Tax effects on sale of assets	(89,473)
Malaysia [Member]
Tax effects on sale of assets	$ 2,080	$ (122,559)	$ (227,241)