Debt, Interest Rate Swap Arrangements (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Cross Currency Interest Rate Contract [Member]
Debt Instrument [Line Items]
Proceeds from Hedge, Investing Activities		$ 44
Notional Amount Of Derivatives		$ 900	$ 1,500
Interest Rate Swap, Pay Rate at Period End		1.14%
Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Payments for Hedge, Financing Activities		$ 17
Notional Amount Of Derivatives		$ 1,000	$ 3,100
Interest Rate Swap, Pay Rate at Period End		3.50%
Senior Notes [Member] | 3.00% Senior Notes Due 2023 [Member] | Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Notional Amount Of Derivatives	[1]	$ 1,000
Interest Rate Swap, Pay Rate Spread above One-month LIBOR		1.764%
Interest Rate Swap, Pay Rate at Period End	[1]	3.5038%
Interest Rate Swap, Fixed Receive Rate		3.00%

[1] The payments on $900 million notional value of these interest rate swaps are offset in part by cross-currency interest rate swaps which effectively reduced the pay rate as of December 31, 2019 from a weighted average of 3.50% to a weighted average of 1.14%.