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Earnings Per Share (Narrative) (Details) - USD ($) |  | 12 Months Ended |
--- | --- | --- | ---
Jul. 24, 2019 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Oct. 28, 2020
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |
Stock repurchase program, shares acquired (in shares) |  | 3,338,028 | 1,898,023 | 1,994,632 |
Common stock acquired |  | $ 399,600,000 | $ 165,800,000 | $ 144,400,000 |
Stock repurchase program, average price per share (in dollars per share) |  | $ 119.70 | $ 87.35 | $ 72.39 |
July 2019 Share Repurchase Program |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |
Stock repurchase program, authorized amount | $ 400,000,000 |  |  |  |
Stock repurchase program period | 2 years |  |  |  |
Stock repurchase program, shares acquired (in shares) |  | 2,368,374 | 1,393,626 |  |
Common stock acquired |  | $ 274,600,000 | $ 125,000,000.0 |  |
Stock repurchase program, average price per share (in dollars per share) |  | $ 115.93 | $ 89.70 |  |
October 2020 Share Repurchase Program |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |
Stock repurchase program, authorized amount |  |  |  |  | $ 500,000,000
Stock repurchase program, shares acquired (in shares) |  | 969,654 |  |  |
Common stock acquired |  | $ 125,000,000.0 |  |  |
Stock repurchase program, average price per share (in dollars per share) |  | $ 128.91 |  |  |
Stock repurchase program, remaining amount | $ 375,000,000.0 |  |  |  |
Other Share Repurchase Programs |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |
Stock repurchase program, shares acquired (in shares) |  |  | 504,397 |  |
Common stock acquired |  |  | $ 40,800,000 |  |
Stock repurchase program, average price per share (in dollars per share) |  |  | $ 80.85 |  |

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- Definition Period which shares may be purchased under a stock repurchase plan authorized by an entity's Board of Directors, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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