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Goodwill and Identifiable Assets Goodwill (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021
Goodwill [Roll Forward] |  |
Gross goodwill, period start | $ 1,569.5 | $ 1,420.7
Purchase price adjustment | (8.1) | 3.3
Translation adjustment | (1.4) | (0.4)
Gross goodwill, period end | 1,891.9 | 1,569.5
Commercial Business |  |
Goodwill [Roll Forward] |  |
Gross goodwill, period start | 829.3 | 778.6
Purchase price adjustment | 0.4 | 0.0
Translation adjustment | (1.4) | (0.4)
Gross goodwill, period end | 1,074.7 | 829.3
Federal Government Business |  |
Goodwill [Roll Forward] |  |
Gross goodwill, period start | 740.2 | 642.1
Purchase price adjustment | (8.5) | 3.3
Translation adjustment | 0.0 | 0.0
Gross goodwill, period end | 817.2 | 740.2
2021 Acquisitions |  |
Goodwill [Roll Forward] |  |
Acquisitions |  | 145.9
Goodwill, expected tax deductible amount | 127.2 |
2021 Acquisitions | Commercial Business |  |
Goodwill [Roll Forward] |  |
Acquisitions |  | 51.1
2021 Acquisitions | Federal Government Business |  |
Goodwill [Roll Forward] |  |
Acquisitions |  | $ 94.8
2022 Acquisitions |  |
Goodwill [Roll Forward] |  |
Acquisitions | 331.9 |
Goodwill, expected tax deductible amount | 250.7 |
2022 Acquisitions | Commercial Business |  |
Goodwill [Roll Forward] |  |
Acquisitions | 246.4 |
2022 Acquisitions | Federal Government Business |  |
Goodwill [Roll Forward] |  |
Acquisitions | $ 85.5 |

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- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 55 -Paragraph 24 -URI https://asc.fasb.org/extlink&oid=122137925&loc=d3e14258-109268 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267 + Details
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- Definition Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267 + Details
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