Pension Plans, Postretirement and Other Employee Benefits - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Pension
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Employer contributions, remainder of fiscal year	$ 11
Postretirement
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Employer contributions	2
Employer contributions, remainder of fiscal year	7
US | Pension
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Employer contributions	1
Foreign | Pension
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Employer contributions	$ 3