Other Income and Expense - Other Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Schedule of Other Nonoperating Income [Line Items]
Other income	$ 30	$ 13
Other Income [Member]
Schedule of Other Nonoperating Income [Line Items]
Insured Event, Gain (Loss)	23	0
Public Utilities, Allowance for Funds Used During Construction, Additions	1	5
Other Nonoperating Income	30	13
Other income	$ 6	$ 8