Employee Retirement Benefits - Net Periodic Income Cost Recognizedf for OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Total	$ 21	$ 42	$ 43
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service benefit (net of $3 and $3 tax expense, respectively)	4	0	4
Net losses (net of $16, $27 and $29 tax benefit, respectively)	(26)	(44)	(45)
Amortization of prior service benefit	0	0	1
Total	(22)	(44)	(40)
Tax effects on components of net periodic income (cost) recognized in OCI [Abstract]
Prior service benefit (cost)	3	0	3
Net gains (losses)	$ (16)	$ (27)	$ (29)