v3.26.3
Treasury Stock and Share-Based Awards - Summary of Restricted Stock and Restricted Stock Unit Award Activity (Detail) - USD ($)
shares in Thousands, $ in Millions
 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Restricted Stock    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of restricted stock units that vested during the period 930  
Compensation expense recognized during the period [1],[2] $ 12.4 $ 12.6
Fair value of restricted stock that vested during the period 25.2 39.2
Income tax benefit recognized upon vesting of restricted stock awards held by 4.8 7.0
Restricted Stock | CUSA Employees [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Compensation expense recognized during the period [1],[2] 11.3 11.6
Fair value of restricted stock that vested during the period 23.8 36.8
Income tax benefit recognized upon vesting of restricted stock awards held by 4.4 6.5
Restricted Stock | Holdings Directors [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Compensation expense recognized during the period 1.1 1.0
Fair value of restricted stock that vested during the period 1.4 2.4
Income tax benefit recognized upon vesting of restricted stock awards held by $ 0.4 $ 0.5
Restricted Stock Units (RSUs)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of restricted stock units that vested during the period 100 0
Compensation expense recognized during the period $ 2.4 $ 1.0
Fair value of restricted stock that vested during the period 2.2 0.0
Income tax benefit recognized upon vesting of restricted stock awards held by 0.2 0.0
Accumulated dividends paid upon vesting of restricted stock units $ 0.0 $ 0.0
Performance Shares [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of restricted stock units that vested during the period 1,400 800
Compensation expense recognized during the period [3] $ 13.3 $ 12.5
Fair value of restricted stock that vested during the period 37.3 20.6
Income tax benefit recognized upon vesting of restricted stock awards held by 5.5 2.5
Accumulated dividends paid upon vesting of restricted stock units $ 0.5 $ 0.0
[1] Compensation expense for the nine months ended September 30, 2026 and 2025 includes approximately $0.6 and $0.9, respectively, related to a portion of the short-term field incentive compensation plan for 2026 and 2025, respectively, to be settled in restricted stock.
[2] Compensation expense for the nine months ended September 30, 2026 includes approximately $0.2 related to the modification of certain outstanding restricted stock awards that permits eligible employees to continue vesting in outstanding awards following retirement, subject to certain conditions and obligations approved by Holdings’ Compensation Committee. The Company determined the revised requisite service period of the modified awards to be the shorter of the period until retirement eligibility or the original vesting period.
[3] Compensation expense for the three and nine months ended September 30, 2026 includes approximately $0.1 related to the modification of certain outstanding PSUs that permits eligible employees to continue vesting in outstanding awards following retirement, subject to certain conditions and obligations approved by Holdings’ Compensation Committee. The Company determined the revised requisite service period of the modified awards to be the shorter of the period until retirement eligibility or the original vesting period.