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Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Jun. 02, 2021 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Increase (decrease) in stock-based compensation from change in management's estimate |  |  |  | $ 3,209 | $ 0
Unrecognized compensation cost |  | $ 72,399 |  | 72,399 |
Total intrinsic value of options exercised |  |  |  | 30,496 |
Aggregate intrinsic value of options exercisable |  | $ 104,146 |  | $ 104,146 |
Market value of Company's common stock (in USD per share) |  | $ 59.30 |  | $ 59.30 |
Weighted average exercise price per share (in USD per share) |  | $ 40.63 |  | $ 40.63 |
Total options outstanding (in shares) |  | 16,925 |  | 16,925 |
Total options exercisable (in shares) |  | 5,578 |  | 5,578 |
Dividends declared per common share (in USD per share) | $ 0.37 | $ 0 | $ 0 | $ 0.37 | $ 0.35
Cash dividends declared |  |  |  | $ 52,389 | $ 51,462
Common Stock Buyback |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Shares purchased and retired (in shares) |  |  |  | 5,218 |
Company purchased, cost |  |  |  | $ 316,053 |
Remaining stock repurchase authorization amount |  | $ 126,775 |  | $ 126,775 |
2014 Plan | Tranche One |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Vesting rate |  |  |  | 50.00% |
2014 Plan | Tranche Two |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Vesting rate |  |  |  | 50.00% |
Minimum |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award waiting period |  |  |  | 2 years |
Maximum |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award waiting period |  |  |  | 4 years |

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- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 + Details
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