Income Taxes (Schedule of Effective Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Total pre-tax income (loss) from continuing operations	$ 1,427	$ (454)	$ (1,164)
Total income tax expense (benefit)	$ 331	$ 376	$ 923
Effective income tax rate on continuing operations	23.00%	83.00%	79.00%
Income taxes at the statutory tax rate	$ 300	$ (159)	$ (407)
Effects of foreign operations	214	140	47
Adjustments to valuation allowances	(177)	446	1,270
State income taxes	(17)	(19)	9
Tax law change	0	(35)	6
Other federal tax effects	$ 11	$ 3	$ (2)