v3.26.1
Business Combinations, Acquisitions, and Business Disposals - Schedule of Fair Value of Net Assets Acquired (Details) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Dec. 01, 2025
Jul. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
Business Combination, Consideration Transferred [Abstract]            
Goodwill $ 1,861.7 $ 1,872.4     $ 1,861.7  
Measurement period Adjustments, Goodwill         1.4  
GAAP purchase consideration, net of cash acquired         0.2 $ 0.0
Nuclear & Safety            
Business Combination, Consideration Transferred [Abstract]            
Goodwill $ 1,227.7 1,238.4     1,227.7  
Measurement period Adjustments, Goodwill         1.4  
Certrec Corporation            
Business Combination, Consideration Transferred [Abstract]            
Purchase consideration         $ 82.9  
GAAP purchase consideration, net of cash acquired       $ 80.6    
Certrec Corporation | Leasehold Improvements            
Business Combination, Consideration Transferred [Abstract]            
Useful life 3 years 7 months 6 days       3 years 7 months 6 days  
Certrec Corporation | Developed technology | Minimum            
Business Combination, Consideration Transferred [Abstract]            
Useful life 5 years       5 years  
Certrec Corporation | Developed technology | Maximum            
Business Combination, Consideration Transferred [Abstract]            
Useful life 15 years       15 years  
Certrec Corporation | Customer relationships            
Business Combination, Consideration Transferred [Abstract]            
Useful life 10 years       10 years  
Certrec Corporation | Trade names            
Business Combination, Consideration Transferred [Abstract]            
Useful life 10 years       10 years  
Certrec Corporation | Backlog            
Business Combination, Consideration Transferred [Abstract]            
Useful life 3 years       3 years  
Certrec Corporation | Nuclear & Safety            
Business Combination, Consideration Transferred [Abstract]            
Goodwill $ 55.7       $ 55.7  
Total amortizable intangible assets 29.9       29.9  
Cash 2.3       2.3  
Restricted cash—current 0.0       0.0  
Accounts receivable, net 0.7       0.7  
Costs in excess of billings 0.0       0.0  
Inventories 0.0       0.0  
Prepaid expenses and other currents assets 0.1       0.1  
Property, plant, and equipment, net 0.0       0.0  
Other assets 0.8       0.8  
Accounts payable (0.3)       (0.3)  
Deferred contract revenue (4.2)       (4.2)  
Accrued expenses and other current liabilities (1.6)       (1.6)  
Deferred income taxes, non-current 0.0       0.0  
Other liabilities, non-current (0.5)       (0.5)  
Net tangible assets acquired (2.7)       (2.7)  
Less: cash and restricted cash acquired         2.3  
GAAP purchase consideration, net of cash acquired         80.6  
Certrec Corporation | Nuclear & Safety | Leasehold Improvements            
Business Combination, Consideration Transferred [Abstract]            
Total amortizable intangible assets 0.0       0.0  
Certrec Corporation | Nuclear & Safety | Developed technology            
Business Combination, Consideration Transferred [Abstract]            
Total amortizable intangible assets 19.9       19.9  
Certrec Corporation | Nuclear & Safety | Customer relationships            
Business Combination, Consideration Transferred [Abstract]            
Total amortizable intangible assets 8.6       8.6  
Certrec Corporation | Nuclear & Safety | Trade names            
Business Combination, Consideration Transferred [Abstract]            
Total amortizable intangible assets 1.4       1.4  
Certrec Corporation | Nuclear & Safety | Backlog            
Business Combination, Consideration Transferred [Abstract]            
Total amortizable intangible assets $ 0.0       $ 0.0  
Paragon            
Business Combination, Consideration Transferred [Abstract]            
GAAP purchase consideration, net of cash acquired     $ 581.5      
Paragon | Leasehold Improvements            
Business Combination, Consideration Transferred [Abstract]            
Useful life 3 years 7 months 6 days       3 years 7 months 6 days  
Paragon | Developed technology | Minimum            
Business Combination, Consideration Transferred [Abstract]            
Useful life 5 years       5 years  
Paragon | Developed technology | Maximum            
Business Combination, Consideration Transferred [Abstract]            
Useful life 15 years       15 years  
Paragon | Customer relationships            
Business Combination, Consideration Transferred [Abstract]            
Useful life 10 years       10 years  
Paragon | Trade names            
Business Combination, Consideration Transferred [Abstract]            
Useful life 10 years       10 years  
Paragon | Backlog            
Business Combination, Consideration Transferred [Abstract]            
Useful life 3 years       3 years  
Paragon | Nuclear & Safety            
Business Combination, Consideration Transferred [Abstract]            
Goodwill $ 345.1 343.7     $ 345.1  
Measurement period Adjustments, Goodwill         1.4  
Total amortizable intangible assets 253.7 250.5     253.7  
Measurement period Adjustments, Total amortizable intangible assets         3.2  
Cash 4.6 4.6     4.6  
Measurement period Adjustments, Cash         0.0  
Restricted cash—current 2.5 2.5     2.5  
Measurement period Adjustments, Restricted cash—current         0.0  
Accounts receivable, net 14.3 14.3     14.3  
Measurement period Adjustments, Accounts receivable, net         0.0  
Costs in excess of billings 11.6 12.4     11.6  
Measurement period Adjustments, Costs in excess of billings         (0.8)  
Inventories 15.6 16.3     15.6  
Measurement period Adjustments, Inventories         (0.7)  
Prepaid expenses and other currents assets 2.3 2.3     2.3  
Measurement period Adjustments, Prepaid expenses and other currents assets         0.0  
Property, plant, and equipment, net 1.4 1.4     1.4  
Measurement period Adjustments, Adjustment, Property, plant, and equipment, net         0.0  
Other assets 1.8 2.3     1.8  
Measurement period Adjustments, Other assets         (0.5)  
Accounts payable (6.9) (6.9)     (6.9)  
Measurement period Adjustments, Accounts payable         0.0  
Deferred contract revenue (12.4) (11.0)     (12.4)  
Measurement period Adjustments, Deferred contract revenue         (1.4)  
Accrued expenses and other current liabilities (10.9) (9.9)     (10.9)  
Measurement period Adjustments, Accrued expenses and other current liabilities         (1.0)  
Deferred income taxes, non-current (32.9) (32.9)     (32.9)  
Measurement period Adjustments, Deferred income taxes, non-current         0.0  
Other liabilities, non-current (1.2) (1.2)     (1.2)  
Measurement period Adjustments, Other liabilities, non-current         0.0  
Net tangible assets acquired (10.2) (5.8)     (10.2)  
Net tangible assets acquired         (4.4)  
Purchase consideration 588.6 588.4        
Measurement period Adjustments, Purchase consideration         0.2  
Less: cash and restricted cash acquired 7.1 7.1        
Measurement period Adjustments, Cash and restricted cash acquired         0.0  
GAAP purchase consideration, net of cash acquired 581.5 581.3        
Measurement period Adjustments, GAAP purchase consideration, net of cash acquired         0.2  
Paragon | Nuclear & Safety | Leasehold Improvements            
Business Combination, Consideration Transferred [Abstract]            
Total amortizable intangible assets 2.0 2.0     2.0  
Measurement period Adjustments, Total amortizable intangible assets         0.0  
Paragon | Nuclear & Safety | Developed technology            
Business Combination, Consideration Transferred [Abstract]            
Total amortizable intangible assets 52.1 52.1     52.1  
Measurement period Adjustments, Total amortizable intangible assets         0.0  
Paragon | Nuclear & Safety | Customer relationships            
Business Combination, Consideration Transferred [Abstract]            
Total amortizable intangible assets 174.4 171.3     174.4  
Measurement period Adjustments, Total amortizable intangible assets         3.1  
Paragon | Nuclear & Safety | Trade names            
Business Combination, Consideration Transferred [Abstract]            
Total amortizable intangible assets 12.6 12.6     12.6  
Measurement period Adjustments, Total amortizable intangible assets         0.0  
Paragon | Nuclear & Safety | Backlog            
Business Combination, Consideration Transferred [Abstract]            
Total amortizable intangible assets $ 12.6 $ 12.5     12.6  
Measurement period Adjustments, Total amortizable intangible assets         $ 0.1