CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 65	$ 55	$ 241	$ 193
Other comprehensive income
Change in fair value of cash flow hedges (Note 13)	2		8	1
Amortization of realized loss on derivative financial instruments (Note 13)			2	1
Reclassification to net income of gains and losses on cash flow hedges (Note 13)	1	1	4
Comprehensive income	68	56	255	195
Comprehensive income attributable to non-controlling interests	2	1	11	7
Comprehensive income attributable to controlling interests	$ 66	$ 55	$ 244	$ 188