U.S. Pension Plan Investments Measured at Fair Value (Details) - Pension Plan [Member] - UNITED STATES - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Large Cap Equity Funds	[1]	$ 35	$ 37
Small mid Cap Equity Funds	[1]	5	6
Other International Equity	[1]	25	27
Debt Securities Fixed Income	[1]	107	103
Cash, Money Market and Other	[2]	2	2
Aggregate fair value of plan assets		197	197
Fair value of plan assets at end of year subtotal		174	175
Other funds	[3]	23	22
Fair Value, Inputs, Level 1 [Member]
Large Cap Equity Funds	[1]	0	0
Small mid Cap Equity Funds	[1]	0	0
Other International Equity	[1]	0	0
Debt Securities Fixed Income	[1]	0	0
Cash, Money Market and Other	[2]	0	0
Aggregate fair value of plan assets		0	0
Fair Value, Inputs, Level 2 [Member]
Large Cap Equity Funds	[1]	35	37
Small mid Cap Equity Funds	[1]	5	6
Other International Equity	[1]	25	27
Debt Securities Fixed Income	[1]	107	103
Cash, Money Market and Other	[2]	2	2
Aggregate fair value of plan assets		174	175
Fair Value, Inputs, Level 3 [Member]
Large Cap Equity Funds	[1]	0	0
Small mid Cap Equity Funds	[1]	0	0
Other International Equity	[1]	0	0
Debt Securities Fixed Income	[1]	0	0
Cash, Money Market and Other	[2]	0	0
Aggregate fair value of plan assets		$ 0	$ 0

[1] Level 2 equity and fixed income securities are primarily in pooled asset and mutual funds and are valued based on underlying net asset value multiplied by the number of shares held. The underlying asset values are based on observable inputs and quoted market prices.

[2] Cash equivalents represent investment in a collective short term investment fund, which is a cash sweep for uninvested cash that earns interest monthly. For these investments, book value is assumed to equal fair value due to the short duration of the investment term.

[3] Represents investments in commingled funds with exposure to a variety of hedge fund strategies, which are not publicly traded and have ongoing redemption restrictions. The Company’s interest in these investments is measured at net asset value per share as a practical expedient for fair value, which is derived from the underlying asset values in these funds, only some of which represent observable inputs and quoted market prices