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Business Combinations, Acquisitions, and Business Disposals - Schedule of Fair Value of Net Assets Acquired (Details) - USD ($) $ in Millions |  |  | 12 Months Ended
--- | --- | --- | ---
Dec. 01, 2025 | Jul. 31, 2025 | Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023
Business Combination [Line Items] |  |  |  |  |
Goodwill |  |  | $ 1,872.4 | $ 1,426.2 | $ 1,447.6
GAAP purchase consideration, net of cash acquired |  |  | 661.9 | 1.0 | 31.4
Nuclear & Safety |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Goodwill |  |  | $ 1,238.4 | $ 792.2 | $ 814.2
Certrec |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Purchase consideration |  | $ 82.9 |  |  |
GAAP purchase consideration, net of cash acquired |  | 80.6 |  |  |
Certrec | Leasehold Improvements |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 2 years 8 months 12 days |  |
Certrec | Developed technology | Minimum |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 5 years |  |
Certrec | Developed technology | Maximum |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 15 years |  |
Certrec | Customer relationships |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 10 years |  |
Certrec | Trade names |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 10 years |  |
Certrec | Backlog |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 3 years |  |
Certrec | Nuclear & Safety |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Goodwill |  | 55.7 |  |  |
Total amortizable intangible assets |  | 29.9 |  |  |
Cash |  | 2.3 |  |  |
Restricted cash—current |  | 0.0 |  |  |
Accounts receivable, net |  | 0.7 |  |  |
Costs in excess of billings |  | 0.0 |  |  |
Inventories |  | 0.0 |  |  |
Prepaid expenses and other currents assets |  | 0.1 |  |  |
Property, plant, and equipment, net |  | 0.0 |  |  |
Other assets |  | 0.8 |  |  |
Accounts payable |  | (0.3) |  |  |
Deferred contract revenue |  | (4.2) |  |  |
Accrued expenses and other current liabilities |  | (1.6) |  |  |
Deferred income taxes, non-current |  | 0.0 |  |  |
Other liabilities, non-current |  | (0.5) |  |  |
Net tangible assets acquired |  | (2.7) |  |  |
Purchase consideration |  | 82.9 |  |  |
Less: cash and restricted cash acquired |  | 2.3 |  |  |
GAAP purchase consideration, net of cash acquired |  | 80.6 |  |  |
Acquiree revenue post acquisition through the period ended December 31, 2025 |  | 6.1 |  |  |
Acquiree loss from operations post acquisition through the period ended December 31, 2025 |  | (0.4) |  |  |
Certrec | Nuclear & Safety | Leasehold Improvements |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Total amortizable intangible assets |  | 0.0 |  |  |
Certrec | Nuclear & Safety | Developed technology |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Total amortizable intangible assets |  | 19.9 |  |  |
Certrec | Nuclear & Safety | Customer relationships |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Total amortizable intangible assets |  | 8.6 |  |  |
Certrec | Nuclear & Safety | Trade names |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Total amortizable intangible assets |  | 1.4 |  |  |
Certrec | Nuclear & Safety | Backlog |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Total amortizable intangible assets |  | $ 0.0 |  |  |
Paragon |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Purchase consideration | $ 588.4 |  |  |  |
GAAP purchase consideration, net of cash acquired | 581.3 |  |  |  |
Paragon | Leasehold Improvements |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 2 years 8 months 12 days |  |
Paragon | Developed technology | Minimum |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 5 years |  |
Paragon | Developed technology | Maximum |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 15 years |  |
Paragon | Customer relationships |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 10 years |  |
Paragon | Trade names |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 10 years |  |
Paragon | Backlog |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Useful life |  |  | 3 years |  |
Paragon | Nuclear & Safety |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Goodwill | 343.7 |  |  |  |
Total amortizable intangible assets | 250.5 |  |  |  |
Cash | 4.6 |  |  |  |
Restricted cash—current | 2.5 |  |  |  |
Accounts receivable, net | 14.3 |  |  |  |
Costs in excess of billings | 12.4 |  |  |  |
Inventories | 16.3 |  |  |  |
Prepaid expenses and other currents assets | 2.3 |  |  |  |
Property, plant, and equipment, net | 1.4 |  |  |  |
Other assets | 2.3 |  |  |  |
Accounts payable | (6.9) |  |  |  |
Deferred contract revenue | (11.0) |  |  |  |
Accrued expenses and other current liabilities | (9.9) |  |  |  |
Deferred income taxes, non-current | (32.9) |  |  |  |
Other liabilities, non-current | (1.2) |  |  |  |
Net tangible assets acquired | (5.8) |  |  |  |
Purchase consideration | 588.4 |  |  |  |
Less: cash and restricted cash acquired | 7.1 |  |  |  |
GAAP purchase consideration, net of cash acquired | 581.3 |  |  |  |
Acquiree revenue post acquisition through the period ended December 31, 2025 | 9.0 |  |  |  |
Acquiree loss from operations post acquisition through the period ended December 31, 2025 | (1.8) |  |  |  |
Paragon | Nuclear & Safety | Leasehold Improvements |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Total amortizable intangible assets | 2.0 |  |  |  |
Paragon | Nuclear & Safety | Developed technology |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Total amortizable intangible assets | 52.1 |  |  |  |
Paragon | Nuclear & Safety | Customer relationships |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Total amortizable intangible assets | 171.3 |  |  |  |
Paragon | Nuclear & Safety | Trade names |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Total amortizable intangible assets | 12.6 |  |  |  |
Paragon | Nuclear & Safety | Backlog |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Total amortizable intangible assets | $ 12.5 |  |  |  |

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