Income Taxes (Unrecognized Tax Benefits Information) (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, net of federal tax benefits, that would impact the effective tax rate	$ 80	$ 67	$ 70
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	2	(2)	2
Payable related to accrued interest and penalties	10	8
Reconciliation of gross unrecognized tax benefits (expense)
Beginning balance	100	92	76
Additions based on tax positions related to the current year	11	15	22
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions	(1)
Additions for tax positions of prior years	10	39	9
Reductions for tax positions of prior years	(4)	(17)	(3)
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	(5)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(1)	(29)	(12)
Ending balance	110	$ 100	$ 92
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in gross amount of unrecognized tax benefits due to resolution of IRS examinations	20
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in gross amount of unrecognized tax benefits due to resolution of IRS examinations	$ 30