Income Taxes - (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Increase (Decrease) in Deferred Income Taxes	$ (427)
Income taxes (benefit)	(367)	$ 235
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	$ (614)	$ (828)
Effective Income Tax Rate Reconciliation, Percent	59.80%
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 502
Valuation Allowance, U.S. Federal Tax Credit Carryforwards, Increase (Decrease), Amount	164
Valuation Allowance, Foreign NOLs, Increase (Decrease), Amount	110
Valuation Allowance, State NOLs, Increase (Decrease), Amount	15
Valuation Allowance, Other U.S. Deferred Tax Assets, Increase (Decrease), Amount	213
Increase (Decrease) in Income Taxes Receivable	484
Increase (Decrease) in Income Taxes Receivable, Current	$ 324