Goodwill and Other Intangible Assets - Goodwill by Reportable Segments (Detail) - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2023 |
Sep. 30, 2023 |
Dec. 31, 2022 |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
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| Goodwill [Line Items] | ||||||||||
| Goodwill, gross, Beginning balance | $ 5,599.7 | $ 5,586.3 | $ 5,599.7 | $ 5,586.3 | $ 5,626.0 | |||||
| Accumulated Impairment Losses | (2,085.3) | (1,513.9) | (2,085.3) | (1,513.9) | (394.3) | |||||
| Goodwill, net | 3,514.4 | [1] | 4,072.4 | 3,514.4 | [1] | 4,072.4 | 5,231.7 | |||
| Additions (Deductions) | 0.0 | 0.0 | ||||||||
| Impairment | (571.4) | (1,119.6) | ||||||||
| Foreign Exchange and Other | 13.4 | (39.7) | ||||||||
| Goodwill, gross, Ending balance | 5,599.7 | 5,586.3 | 5,599.7 | 5,586.3 | ||||||
| CCS [Member] | ||||||||||
| Goodwill [Line Items] | ||||||||||
| Goodwill, gross, Beginning balance | 2,291.0 | 2,280.9 | 2,291.0 | 2,280.9 | 2,307.3 | |||||
| Accumulated Impairment Losses | (150.6) | (51.5) | (150.6) | (51.5) | (51.5) | |||||
| Goodwill, net | 2,140.4 | [1] | 2,229.4 | 2,140.4 | [1] | 2,229.4 | 2,255.8 | |||
| Additions (Deductions) | 0.0 | 0.0 | ||||||||
| Impairment | (99.1) | 0.0 | ||||||||
| Foreign Exchange and Other | 10.1 | (26.4) | ||||||||
| Goodwill, gross, Ending balance | 2,291.0 | 2,280.9 | 2,291.0 | 2,280.9 | ||||||
| OWN [Member] | ||||||||||
| Goodwill [Line Items] | ||||||||||
| Goodwill, gross, Beginning balance | 662.7 | 660.3 | 662.7 | 660.3 | 666.6 | |||||
| Accumulated Impairment Losses | (159.5) | (159.5) | (159.5) | (159.5) | (159.5) | |||||
| Goodwill, net | 503.2 | [1] | 500.8 | 503.2 | [1] | 500.8 | 507.1 | |||
| Additions (Deductions) | 0.0 | 0.0 | ||||||||
| Impairment | 0.0 | 0.0 | ||||||||
| Foreign Exchange and Other | 2.4 | (6.3) | ||||||||
| Goodwill, gross, Ending balance | 662.7 | 660.3 | 662.7 | 660.3 | ||||||
| NICS [Member] | ||||||||||
| Goodwill [Line Items] | ||||||||||
| Goodwill, gross, Beginning balance | 650.6 | 649.4 | 650.6 | 649.4 | 653.0 | |||||
| Accumulated Impairment Losses | (41.2) | (41.2) | (41.2) | (41.2) | (41.2) | |||||
| Goodwill, net | 609.4 | [1] | 608.2 | 609.4 | [1] | 608.2 | 611.8 | |||
| Additions (Deductions) | 0.0 | 0.0 | ||||||||
| Impairment | 0.0 | 0.0 | ||||||||
| Foreign Exchange and Other | 1.2 | (3.6) | ||||||||
| Goodwill, gross, Ending balance | 650.6 | 649.4 | 650.6 | 649.4 | ||||||
| ANS [Member] | ||||||||||
| Goodwill [Line Items] | ||||||||||
| Goodwill, gross, Beginning balance | 1,995.4 | 1,995.7 | 1,995.4 | 1,995.7 | 1,999.1 | |||||
| Accumulated Impairment Losses | (1,734.0) | (1,261.7) | (1,734.0) | (1,261.7) | (142.1) | |||||
| Goodwill, net | 261.4 | [1] | 734.0 | 261.4 | [1] | 734.0 | $ 1,857.0 | |||
| Additions (Deductions) | 0.0 | 0.0 | ||||||||
| Impairment | (46.4) | $ (425.9) | (1,119.6) | (472.3) | (1,119.6) | |||||
| Foreign Exchange and Other | (0.3) | (3.4) | ||||||||
| Goodwill, gross, Ending balance | $ 1,995.4 | $ 1,995.7 | $ 1,995.4 | $ 1,995.7 | ||||||
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