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Stock-Based Compensation - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense for stock-based compensation plans	$ 104,000,000	$ 101,000,000	$ 96,000,000
Total income tax benefit recognized for stock-based compensation plans	$ 25,000,000	$ 24,000,000	$ 23,000,000
Common Shares available for future grant under compensation plans (in shares)	34,121,863
Maximum percentage of outstanding common stock that may be granted as options	6.00%
Rolling period in which a certain percentage of common stock cannot be granted as options	3 years
Exercise rate of stock options granted to employees	25.00%
Vesting period for compensation cost	4 years
Authorized number of shares that may be issued as equity awards (in shares)			71,600,000
Common shares, issued (in shares)	1,256,702,081	1,256,702,081
Weighted-average grant-date fair value of options (in dollars per share)	$ 3.38	$ 2.96	$ 3.07
Number of options, exercised (in shares)	2,319,438
Total intrinsic value of exercised options	$ 22,000,000	$ 5,000,000	$ 18,000,000
Cash received from options exercised	$ 27,000,000	8,000,000	18,000,000
Actual tax benefit realized for tax deductions from options exercised		$ 1,000,000	$ 1,000,000
Mandatory deferred incentive awards, vesting rate (as a percent)	25.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares, issued (in shares)			3,000,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options expiration years	10 years
Number of options, exercised (in shares)	2,319,438	821,916	2,039,208
Unrecognized compensation cost related to nonvested options expected to vest	$ 1,000,000
Weighted-average period	2 years 4 months 24 days
Stock Options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for compensation cost	1 year
Stock Options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options expiration years	10 years
Deferred Cash Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	25.00%
Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	25.00%
Equity Based Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Cash Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Deferred Compensation Plans and Other Restricted Stock Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value granted (in dollars per share)	$ 21.25	$ 16.22	$ 17.57
Deferred Compensation Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested options expected to vest	$ 25,000,000
Weighted-average period	3 years 1 month 6 days
Fair value of units/shares vested	$ 16,000,000	$ 18,000,000	$ 19,000,000
Long-Term Incentive Compensation Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested options expected to vest	$ 97,000,000
Weighted-average period	2 years 3 months 18 days
Fair value of units/shares vested	$ 105,000,000	$ 89,000,000	$ 89,000,000
Weighted-average grant-date fair value granted (in dollars per share)	$ 20.06	$ 18.68	$ 18.25
Discounted Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee discount on the purchase of stock through Discounted Stock Purchase Plan	10.00%
Purchases are limited to any month	$ 10,000
Purchases are limited to any calendar year	$ 50,000
Issuance of common shares (in shares)	335,951	500,508	327,243
Weighted-average cost of common shares issued under the plan (in dollars per share)	$ 19.28	$ 11.76	$ 15.73
Vesting Contingent on Performance and Service Conditions - Payable in Stock \| Long-Term Incentive Compensation Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value granted (in dollars per share)	$ 19.07
Vesting Contingent on Performance and Service Conditions - Payable in Stock \| Long-Term Incentive Compensation Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance units vested (in shares)		421,352
Vesting Contingent on Performance and Service Conditions - Payable in Stock \| Long-Term Incentive Compensation Program \| Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units/shares vested		$ 8,000,000
Vesting Contingent on Performance and Service Conditions - Payable in Cash \| Long-Term Incentive Compensation Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance units vested (in shares)	1,278,629
Weighted-average grant-date fair value granted (in dollars per share)	$ 23.19
Vesting Contingent on Performance and Service Conditions - Payable in Cash \| Long-Term Incentive Compensation Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance units vested (in shares)		654,108
Vesting Contingent on Performance and Service Conditions - Payable in Cash \| Long-Term Incentive Compensation Program \| Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units/shares vested	$ 23,000,000	$ 13,000,000