XML 123 R102.htm IDEA: XBRL DOCUMENT v3.22.0.1
Other Comprehensive Income (Loss) And Accumulated Other Comprehensive Income - Other Comprehensive Income (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Other Comprehensive Income (Loss)        
Decrease (Increase) in Net Unrecognized Postretirement Benefit Costs $ (8.8) $ 70.2 $ (7.8)  
Other Comprehensive Income (Loss) Before Income Taxes (294.8) 437.9 397.9  
Other Comprehensive Income (Loss) before Income Taxes        
Unrealized Holding Gains and Losses (60.1) (78.3) (85.2)  
Tax Effects from Postretirement Benefit Plans (2.4) (15.3) 1.7  
Other Comprehensive Income Tax Benefit (Expense) 62.4 (93.5) (83.6)  
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Stockholders' Equity Attributable to Parent 4,007.7 4,563.4    
Accumulated Net Unrealized Investment Gain (Loss)        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Stockholders' Equity Attributable to Parent (3.7) (2.1) 0.0 $ 0.0
OCI, before Reclassifications, Net of Tax, Attributable to Parent (1.6) (2.1) 0.0  
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent 0.0 0.0 0.0  
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent (1.6) (2.1) 0.0  
Accumulated Defined Benefit Plans Adjustment        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Stockholders' Equity Attributable to Parent (52.1) (45.7) (100.6)  
OCI, before Reclassifications, Net of Tax, Attributable to Parent (6.5) 4.3 (6.1)  
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent 0.1 50.6 0.0  
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent (6.4) 54.9 (6.1)  
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Stockholders' Equity Attributable to Parent (1.9) (2.3) (2.7)  
OCI, before Reclassifications, Net of Tax, Attributable to Parent 0.0 0.4 0.3  
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent 0.4 0.0 0.0  
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent 0.4 0.4 0.3  
Accumulated Other Comprehensive Income (Loss)        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Stockholders' Equity Attributable to Parent 448.1 680.5 336.1 $ 21.8
OCI, before Reclassifications, Net of Tax, Attributable to Parent (190.1) 307.0 336.6  
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent (42.3) 37.4 (22.3)  
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent $ (232.4) $ 344.4 $ 314.3