Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Income Tax Examination [Line Items]
Effective income tax rate	(3.40%)	31.50%	5.80%	31.50%
Unrecognized Tax Benefits	$ 1,378		$ 1,378		$ 1,617
Tax Year 2011-2012 [Member]
Income Tax Examination [Line Items]
Tax benefit related to settlement of 2011-2012 federal tax audit	177
Tax Basis Restoration [Member]
Income Tax Examination [Line Items]
Effective Income Tax Rate Reconciliation, Tax Credit, Tax Basis Adjustment	$ 440