XML 20 R3.htm IDEA: XBRL DOCUMENT v3.25.0.1
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Statement of Comprehensive Income [Abstract]      
Net income $ 441.5 $ 416.8 $ 665.7
Pension Plan and Restoration of Retirement Income Plan:      
Amortization of prior service cost, net of tax of $0.1, $0.1 and $0.1, respectively 0.2 0.2 0.2
Amortization of deferred net loss, net of tax of $0.1, $0.2 and $0.2, respectively 0.2 0.9 1.4
Net (loss) gain arising during the period, net of tax of $0.0, $1.0 and ($2.4), respectively (0.2) 3.3 (7.6)
Regulatory classification of certain pension costs, net of tax of $1.2, $0.0 and $0.0, respectively 3.9 0.0 0.0
Settlement cost, net of tax of $0.0, $0.4 and $4.3, respectively 0.0 1.2 13.6
Postretirement benefit plans:      
Amortization of prior service credit, net of tax of $0.0, $0.0 and ($0.1), respectively 0.0 0.0 (0.2)
Amortization of deferred net gain, net of tax of $(0.1), ($0.1) and $0.0, respectively (0.1) (0.1) 0.0
Net gain (loss) arising during the period, net of tax of $0.2, ($0.2) and $1.7, respectively 0.5 (0.8) 5.5
Other comprehensive income, net of tax 4.5 4.7 12.9
Comprehensive income $ 446.0 $ 421.5 $ 678.6