Income Taxes (Unrecognized Tax Benefits Information) (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, net of federal tax benefits, that would impact the effective tax rate	$ 46	$ 57	$ 57
Increase (decrease) in interest and penalties	43	3	6
Payable related to accrued interest and penalties	8	51
Reconciliation of gross unrecognized tax benefits (expense)
Beginning balance	161	242	209
Additions based on tax positions related to the current year	15	18	17
Additions for tax positions of prior years	33	48	35
Reductions for tax positions of prior years	(87)	(147)	(19)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(7)
Ending balance	115	$ 161	$ 242
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in gross amount of unrecognized tax benefits due to resolution of IRS examinations	60
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in gross amount of unrecognized tax benefits due to resolution of IRS examinations	$ 70