Discontinued Operations Income Statement (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Expenses
Net income from discontinued operations	$ 1	$ 821	$ 7	$ 861
Tempo Business | Discontinued Operations, Disposed of by Sale
Revenue
Total revenue	0	171	0	698
Expenses
Total operating expenses	0	156	3	626
Income (loss) from discontinued operations before income taxes	0	26	(3)	83
Income tax expense (benefit)	0	3	(1)	20
Income (loss) from discontinued operations excluding gain, net of tax	0	23	(2)	63
Gain on sale of discontinued operations, net of tax	1	798	9	798
Net income from discontinued operations	$ 1	$ 821	$ 7	$ 861