Income Taxes (Unrecognized Tax Benefits Information) (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, net of federal tax benefits, that would impact the effective tax rate	$ 70	$ 58	$ 46
Increase (decrease) in interest and penalties	2	0	(43)
Payable related to accrued interest and penalties	10	8
Reconciliation of gross unrecognized tax benefits (expense)
Beginning balance	76	115	161
Additions based on tax positions related to the current year	22	16	15
Additions for tax positions of prior years	9	3	33
Reductions for tax positions of prior years	(3)	(57)	(87)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(12)	(1)	(7)
Ending balance	92	$ 76	$ 115
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in gross amount of unrecognized tax benefits due to resolution of IRS examinations	30
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in gross amount of unrecognized tax benefits due to resolution of IRS examinations	$ 40