Benefit Plans (Amounts Recognized in the Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
AMOUNTS RECOGNIZED ON THE CONSOLIDATED BALANCE SHEETS
Accrued benefit liability—noncurrent	$ (230)	$ (237)
Foreign Plan [Member]
AMOUNTS RECOGNIZED ON THE CONSOLIDATED BALANCE SHEETS
Noncurrent assets	69	60
Accrued benefit liability—current	(6)	(5)
Accrued benefit liability—noncurrent	(78)	(64)
Net amount recognized at end of year	(15)	(9)
UNITED STATES
AMOUNTS RECOGNIZED ON THE CONSOLIDATED BALANCE SHEETS
Noncurrent assets	0	0
Accrued benefit liability—current	0	0
Accrued benefit liability—noncurrent	(130)	(144)
Net amount recognized at end of year	$ (130)	$ (144)