Employee Benefits (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions		$ 0	$ 0	$ 0
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year		$ 3
Defined Benefit Plan, Benefits Paid	$ 16
Contribution to health reimbursement account - sick time		58.00%
Contribution to health reimbursement account - earned time off		100.00%
OtherPostretirementDefinedBenefitPlanLiabilityCurrent		$ 2	$ 2
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year		15
Net actuarial loss portion of amortization from AOCL for pension benefits		13
Net Actuarial Loss Portion of Amortization from AOCL for Non-qualified benefits		1
Net actuarial loss portion of amortiztion of AOCL for other postretirement benefits		$ 1
Defined benefit plan, current annual rate of health care cost increase		7.00%	6.50%	7.00%
Defined Benefit Plan, Description of Direction and Pattern of Change for Assumed Health Care Cost Trend Rate		0.065	0.06
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year		0.25%	0.25%	0.50%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate		5.00%	5.00%	5.00%
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components		$ 0
Company match pre 2009 hire		6.00%
Company match post 2008 hire		5.00%
Company contribution percentage to 401k for post 2008 hires		5.00%
Company contribution percent to 401k for bargaining employees		1.00%
401k Plan Company contributions		$ 19	$ 17	$ 16