Fair Value Measurements (Narrative) (Details) kr in Millions		12 Months Ended
	Nov. 05, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 SEK (kr)	Mar. 03, 2020 USD ($)	Mar. 03, 2020 SEK (kr)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Term of agreement	7 years
Aggregate notional amount	$ 550,000,000	$ 546,000,000				$ 550,000,000	$ 650,000,000
Derivative fixed rate	1.615%
Hedging gains and losses in accumulated other comprehensive income expected to be recognized in earnings, net of tax		(6,000,000)
Carrying Value [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total debt		920,000,000				1,735,000,000
Estimated Fair Value [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value of total debt		$ 989,000,000				$ 1,839,000,000
Fixed-To-Fixed Cross-Currency Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Term of agreement		5 years
Derivative, maturity date		Mar. 31, 2025
Aggregate notional amount				$ 74,000,000	kr 725
Fixed-To-Fixed Cross-Currency Interest Rate Swap [Member] | Sweden, Kronor [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fixed rate				3.50%	3.50%
Fixed-To-Fixed Cross-Currency Interest Rate Swap [Member] | United States of America, Dollars [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative fixed rate				4.147%	4.147%
Cross Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Term of agreement		5 years
Derivative, maturity date		Mar. 31, 2025
Aggregate notional amount		$ 131,000,000	kr 1,275
Derivative fixed rate		0.00%	0.00%
Fuel Swap Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Aggregate notional amount		$ 23,000,000
Letters of credit posted as collateral under fuel hedging program		$ 2,000,000