Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Summary of AOCI Activity (Details)

v3.20.4
Stockholders' Equity - Summary of AOCI Activity (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning balance $ 268.3 $ 391.0 $ 550.0
Other comprehensive income (loss) 15.4 (13.1) 3.5
Ending balance 222.6 268.3 391.0
Foreign currency translation adjustments      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning balance (0.5) 1.7  
Other comprehensive (loss) before reclassifications, net of tax impact 7.2 (2.2)  
Amounts reclassified from accumulated other comprehensive (loss) income 0.0 0.0  
Other comprehensive income (loss) 7.2 (2.2) (6.0)
Ending balance 6.7 (0.5) 1.7
AOCI tax (expense) benefit 0.0 0.0  
Derivative Adjustments      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning balance (0.6) 0.8  
Other comprehensive (loss) before reclassifications, net of tax impact (0.2) (0.7)  
Amounts reclassified from accumulated other comprehensive (loss) income 0.2 (0.7)  
Other comprehensive income (loss) (0.4) (1.4) 1.7
Ending balance (1.0) (0.6) 0.8
AOCI tax (expense) benefit 0.2 0.1  
Pension and postretirement adjustments      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning balance (73.6) (64.1)  
Other comprehensive (loss) before reclassifications, net of tax impact 5.9 (16.5)  
Amounts reclassified from accumulated other comprehensive (loss) income 2.7 7.0  
Other comprehensive income (loss) 8.6 (9.5) 7.8
Ending balance (65.0) (73.6) (64.1)
AOCI tax (expense) benefit (2.0) 0.0  
Accumulated other comprehensive (loss) income      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning balance (74.7) (61.6) (52.5)
Other comprehensive (loss) before reclassifications, net of tax impact 12.9 (19.4)  
Amounts reclassified from accumulated other comprehensive (loss) income 2.5 6.3  
Other comprehensive income (loss) 15.4 (13.1) 3.5
Ending balance (59.3) (74.7) $ (61.6)
AOCI tax (expense) benefit $ (1.8) $ 0.1