Employee Benefit Plans - Schedule of Pre-Tax Amounts Recognized in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Defined Pension Benefits
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Prior service cost	$ 0	$ 0
Net actuarial loss (gain)	(71)	(67)
Accumulated other comprehensive (loss) income	(71)	(67)
Other Postretirement Benefits
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Prior service cost	(2)	(1)
Net actuarial loss (gain)	12	8
Accumulated other comprehensive (loss) income	$ 10	$ 7