UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 142	$ 137
Other comprehensive loss, net of tax:
Remeasurements of pension and other postretirement benefits related to equity method investments, net of tax	0	0
Comprehensive income	142	137
Less comprehensive income attributable to noncontrolling interests	4	5
Comprehensive income attributable to the Partnership	$ 138	$ 132