v3.26.1
Stockholders' Equity, Accumulated Other Comprehensive Income (Loss) and Noncontrolling Interest - Change in Stockholders' Equity (Deficit) (Detail) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
Accumulated Other Comprehensive Income (Loss) [Line Items]            
Beginning Balance $ 1,292.8 $ 763.6 $ 813.3 $ 824.5 $ 763.6 $ 824.5
Beginning Balance, shares   40,373,512     40,373,512  
Beginning Balance Treasury Stock, shares   8,164,148     8,164,148  
Net income (loss) 16.0 $ 5.0 2.1 (5.3) $ 21.0 (3.2)
Foreign currency translation (2.3) (2.9) 8.6 0.2    
Changes in defined benefit pension and other post-retirement benefit plans, net of tax (0.2) (0.2) (0.2) (1.0)    
Share repurchases, net of tax (0.8) (1.6)        
Stock-based compensation expense, net 3.5 3.5 3.5 0.7    
Issuance of common stock 0.1 535.4        
Dividends declared to non-controlling interest (0.5) (0.5)        
Cash dividends and dividend equivalents (9.8) (9.5) (6.1) (5.8)    
Ending Balance $ 1,298.8 1,292.8 821.2 813.3 $ 1,298.8 821.2
Ending Balance, shares 60,233,293       60,233,293  
Ending Balance Treasury Stock, shares 8,342,140       8,342,140  
Common Stock [Member]            
Accumulated Other Comprehensive Income (Loss) [Line Items]            
Beginning Balance $ 0.6 $ 0.4 $ 0.4 $ 0.4 $ 0.4 $ 0.4
Beginning Balance, shares 60,228,000 40,374,000 40,358,000 39,899,000 40,374,000 39,899,000
Stock-based compensation expense, net, shares 3,000 326,000 2,000 459,000    
Issuance of common stock   $ 0.2        
Issuance of common stock, shares 2,000 19,528,000        
Ending Balance $ 0.6 $ 0.6 $ 0.4 $ 0.4 $ 0.6 $ 0.4
Ending Balance, shares 60,233,000 60,228,000 40,360,000 40,358,000 60,233,000 40,360,000
Treasury Stock [Member]            
Accumulated Other Comprehensive Income (Loss) [Line Items]            
Beginning Balance $ (240.0) $ (237.0) $ (237.0) $ (234.4) $ (237.0) $ (234.4)
Beginning Balance Treasury Stock, shares (8,303,000) (8,164,000) (8,164,000) (8,051,000) (8,164,000) (8,051,000)
Share repurchases, net of tax $ (0.8) $ (1.6)        
Shares repurchases, net of tax, treasury stock, Shares (39,000) (75,000)        
Stock-based compensation expense, net, treasury stock, shares   (64,000)   (113,000)    
Stock-based compensation expense, net, treasury stock, amount   $ (1.4)   $ (2.6)    
Ending Balance $ (240.8) $ (240.0) $ (237.0) $ (237.0) $ (240.8) $ (237.0)
Ending Balance Treasury Stock, shares (8,342,000) (8,303,000) (8,164,000) (8,164,000) (8,342,000) (8,164,000)
Capital in Excess of Par Value [Member]            
Accumulated Other Comprehensive Income (Loss) [Line Items]            
Beginning Balance $ 973.0 $ 432.6 $ 427.1 $ 423.5 $ 432.6 $ 423.5
Stock-based compensation expense, net 3.5 4.9 3.5 3.3    
Issuance of common stock 0.1 535.2        
Cash dividends and dividend equivalents   0.3   0.3    
Ending Balance 976.6 973.0 430.6 427.1 976.6 430.6
Retained Earnings [Member]            
Accumulated Other Comprehensive Income (Loss) [Line Items]            
Beginning Balance 693.5 698.8 767.9 779.6 698.8 779.6
Net income (loss) 15.5 4.5 1.9 (5.6)    
Cash dividends and dividend equivalents (9.8) (9.8) (6.1) (6.1)    
Ending Balance 699.2 693.5 763.7 767.9 699.2 763.7
Foreign Currency Translation [Member]            
Accumulated Other Comprehensive Income (Loss) [Line Items]            
Beginning Balance (60.6) (57.7) (67.2) (67.5) (57.7) (67.5)
Foreign currency translation (2.2) (2.9) 8.5 0.3    
Ending Balance (62.8) (60.6) (58.7) (67.2) (62.8) (58.7)
Benefit Plan Liabilities [Member]            
Accumulated Other Comprehensive Income (Loss) [Line Items]            
Beginning Balance (84.2) (84.0) (87.3) (86.3) (84.0) (86.3)
Changes in defined benefit pension and other post-retirement benefit plans, net of tax (0.2) (0.2) (0.2) (1.0)    
Ending Balance (84.4) (84.2) (87.5) (87.3) (84.4) (87.5)
Non-controlling Interest [Member]            
Accumulated Other Comprehensive Income (Loss) [Line Items]            
Beginning Balance 10.5 10.5 9.4 9.2 10.5 9.2
Net income (loss) 0.5 0.5 0.2 0.3    
Foreign currency translation (0.1)   0.1 (0.1)    
Dividends declared to non-controlling interest (0.5) (0.5)        
Ending Balance $ 10.4 $ 10.5 $ 9.7 $ 9.4 $ 10.4 $ 9.7