CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 546	$ 482	$ 392
Other comprehensive loss, net of tax:
Remeasurements of pension and other postretirement benefits related to equity method investments, net of tax	(2)	0	0
Comprehensive income	544	482	392
Parent	0	0	77
Noncontrolling interests	18	18	20
Comprehensive income attributable to the Partnership	$ 526	$ 464	$ 295