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Common and Preferred Stock Common and Preferred Stock (Schedule of Activity in the Outstanding Shares of the Company's Common Stock) (Details) - Common Stock [Member] - shares shares in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Increase (Decrease) in Common Stock [Roll Forward] |  |  |
Shares outstanding, beginning balance | 112,132 | 111,129 | 106,615
Awards and sales under employee and director plans | 335 | 329 | 416
5% stock dividend | 5,574 | 5,359 | 5,305
Other purchases of treasury stock | (887) | (4,670) | (1,194)
Other | (16) | (15) | (13)
Shares outstanding, ending balance | 117,138 | 112,132 | 111,129

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