Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income	$ 212	$ 187	$ 193
Other comprehensive (loss) income - Change in compensation retirement benefits liability and amortization, net of taxes of an immaterial amount in 2017, 2016, and 2015	1	(1)	1
Comprehensive income	$ 213	$ 186	$ 194