Schedule I - Condensed Financial Information of Parent (Statement of Comprehensive Income Parenthetical) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Foreign currency translation adjustments, income tax	$ 1	$ 1	$ (7)
Foreign currency, reclassification to earnings, income tax	0	0	0
Change in derivative fair value, income tax	(7)	16	72
Derivative reclassification to earnings, income tax	(8)	(11)	(26)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit), Tax	(6)	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	106	(29)	27
Pension, amortization of net actuarial loss, income tax	(3)	(9)	(7)
Parent Company
Condensed Financial Statements, Captions [Line Items]
Foreign currency translation adjustments, income tax	1	1	(7)
Foreign currency, reclassification to earnings, income tax	0	0	0
Change in derivative fair value, income tax	(5)	4	51
Derivative reclassification to earnings, income tax	1	(12)	(37)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit), Tax	(5)	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	10	(7)	9
Pension, amortization of net actuarial loss, income tax	$ 2	$ (2)	$ 0