UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 167	$ 142
Other comprehensive income, net of tax:
Remeasurements of pension and other postretirement benefits related to equity method investments, net of tax	0	0
Comprehensive income	167	142
Less comprehensive income attributable to noncontrolling interests	4	4
Comprehensive income attributable to the Partnership	$ 163	$ 138