Capital Stock (Changes in Common Stock Outstanding) (Details) - shares shares in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in Common Stock Outstanding [Roll Forward]
Beginning Balance, January 1	180,140	179,724	179,862
Stock incentive plan net activity	986	952	672
Repurchase of common stock	(772)	(536)	(810)
Ending Balance, December 31	180,354	180,140	179,724

Number, after forfeiture, of shares or units issued under share-based payment arrangement. Excludes shares or units issued under employee stock ownership plan (ESOP).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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