Credit Facilities and Debt (Summary of Debt Outstanding) (Details) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Credit Facilities and Long-Term Debt :
Debt issuance costs and unamortized discount	[1]	$ (17)	$ (19)
Long-term debt		2,030	2,051
Total debt		2,336	2,308
Short-term borrowings and current maturities of long-term debt		306	257
Senior Notes Due 2021, 4.875%
Credit Facilities and Long-Term Debt :
Senior Notes Due	[2]	600	600
Senior Notes Due 2023, 2.250%
Credit Facilities and Long-Term Debt :
Senior Notes Due	[2]	547	570
Senior Notes due 2026
Credit Facilities and Long-Term Debt :
Senior Notes Due	[2]	500	500
Senior Notes due 2046
Credit Facilities and Long-Term Debt :
Senior Notes Due	[2]	400	400
Commercial paper
Credit Facilities and Long-Term Debt :
Senior Notes Due		306	0
Term loan
Credit Facilities and Long-Term Debt :
Senior Notes Due		$ 0	$ 257

[1] The debt issuance costs and unamortized discount are recognized as a reduction in the carrying value of the Senior Notes in the Condensed Consolidated Balance Sheets and are being amortized to interest expense in our Condensed Consolidated Income Statements over the expected remaining terms of the Senior Notes.

[2] The fair value of our Senior Notes was determined using quoted prices in active markets for identical securities, which are considered Level 1 inputs. The fair value of our Senior Notes due 2021 was $631 million and $620 million as of September 30, 2019 and December 31, 2018, respectively. The fair value of our Senior Notes due 2023 was $583 million and $599 million as of September 30, 2019 and December 31, 2018, respectively. The fair value of our Senior Notes due 2026 was $515 million and $476 million as of September 30, 2019 and December 31, 2018, respectively. The fair value of our Senior Notes due 2046 was $455 million and $397 million as of September 30, 2019 and December 31, 2018, respectively.