Income Taxes (Unrecognized Tax Benefits Information) (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, net of federal tax benefits, that would impact the effective tax rate	$ 57	$ 57	$ 62
Increase (decrease) in interest and penalties	3	6	6
Payable related to accrued interest and penalties	51	48
Reconciliation of gross unrecognized tax benefits (expense)
Beginning balance	242	209	116
Additions based on tax positions related to the current year	18	17	22
Additions for tax positions of prior years	48	35	74
Reductions for tax positions of prior years	(147)	(19)	(3)
Ending balance	161	$ 242	$ 209
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in gross amount of unrecognized tax benefits due to resolution of IRS examinations	90
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in gross amount of unrecognized tax benefits due to resolution of IRS examinations	$ 100