Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Income from operations of discontinued businesses, income tax expense (benefit)	$ (2)	$ (21)	$ 229
Gain (loss) from disposal and impairment of discontinued businesses, income tax expense (benefit)	$ (44)	$ 0	$ 266

Amount of tax expense (benefit) on gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

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