CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 75	$ 55	$ 177	$ 138
Other comprehensive income
Change in fair value of cash flow hedges (Note 13)	(1)		6	1
Amortization of realized loss on derivative financial instruments (Note 13)	2	1	2	1
Reclassification to net income of gains and losses on cash flow hedges (Note 13)	3	(1)	3	(1)
Comprehensive income	79	55	188	139
Comprehensive income attributable to non-controlling interests	3		9	6
Comprehensive income attributable to controlling interests	$ 76	$ 55	$ 179	$ 133