Schedule II - Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Doubtful Accounts - Current [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		$ 70	$ 70	$ 82
Additions Charged to Earnings		5	9	11
Additions Charged to Other Accounts		0	0	0
Deductions from Reserves	[1]	(2)	(9)	(23)
Balance at End of Period		73	70	70
Restructuring Reserves [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		6	10	16
Additions Charged to Earnings		0	3	5
Additions Charged to Other Accounts		0	0	0
Deductions from Reserves	[2]	(4)	(7)	(11)
Balance at End of Period		$ 2	$ 6	$ 10

[1] Includes write-offs, less recoveries, of accounts determined to be uncollectible and other adjustments.

[2] Includes payments and deductions for reversals of previously established reserves that were no longer required.