Income Taxes (Reconciliation of Income Taxes Based on U.S. Statutory Tax Rate to Income Tax Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes [Abstract]
Income tax expense based on the U.S. statutory tax rate	$ 438,295	$ 515,440	$ 478,804
Foreign income subject to foreign taxes at a rate different than the U.S. statutory rate	20,562	31,752	7,710
State income taxes, net of federal benefit	5,746	4,642	5,268
U.S. tax benefit on certain foreign upstream investments	(95,838)	(133,526)	(108,077)
Deferred tax benefit on sale Malaysian assets	(176,661)
Increase in deferred tax asset valuation allowance related to other foreign exploration expenditures	37,712	129,588	87,558
Impairment or abandonment of Azurite field with no tax benefit		35,475	70,000
Other, net	(2,519)	1,179	20,253
Total	$ 227,297	$ 584,550	$ 561,516