Stockholders' Equity and Equity Instruments (Tables)
 6 Months Ended
Jun. 30, 2021
Equity [Abstract]  
Schedule of Fair Value and Inputs Used to Calculate Fair Value for Options Granted The fair value and inputs used to calculate fair value for options granted for the six months ended June 30, 2021, are included in the table below:
Fair value of options granted$13.46
Exercise price$63.14
Expected term (years)4.75
Expected volatility36.1%
Dividend yield3.7%
Risk-free rate of return0.4%
Summary of Stock-Based Compensation Activity The following table summarizes stock-based compensation activity during the six months ended June 30, 2021:
 Stock OptionsRSUs
PSUs(a)
 NumberWeighted-average
exercise price		NumberWeighted-average
fair value		NumberWeighted-average
fair value
Outstanding at December 31, 2020
868,772 $63.06 207,982 $55.68 241,794 $65.57 
Granted120,602 63.14 95,287 63.52 96,002 63.14 
Exercised(b)
(20,657)60.19 — — — — 
Released from restriction(b)
— — (37,312)55.01 (16,496)69.71 
Cancelled/expired(90,430)79.58 (6,132)62.06 (32,581)61.65 
Outstanding at June 30, 2021
878,287 $61.44 259,825 $58.50 288,719 $64.96 
(a)Until the performance period is completed, PSUs are included in the table at the target level at their grant date and at that level represent one share of common stock per PSU.
(b)Common stock issued for exercised options and for vested and earned RSUs and PSUs was issued from treasury stock.
Summary of Components and Changes in Accumulated Other Comprehensive Income (Loss) The components of and changes in AOCL as of and for the three and six months ended June 30, 2021 and 2020, are as follows (in millions):
Three Months Ended June 30, 2021(a)
Gains and
(Losses) on
Cash Flow
Hedges		Defined
Benefit
Pension		Foreign
Currency		Total
Beginning balance$0.3 $(9.2)$(315.1)$(324.0)
Other comprehensive (loss) income before reclassifications(b)
1.2 — 26.5 27.7 
Amounts reclassified from accumulated other comprehensive (loss) income(0.2)0.3 — 0.1 
Net current period other comprehensive (loss) income1.0 0.3 26.5 27.8 
Ending balance$1.3 $(8.9)$(288.6)$(296.2)

Three Months Ended June 30, 2020(a)
Gains and
(Losses) on
Cash Flow
Hedges		Defined
Benefit
Pension		Foreign
Currency		Total
Beginning balance$(0.5)$(6.7)$(358.5)$(365.7)
Other comprehensive income before reclassifications(b)
0.9 — 2.5 3.4 
Amounts reclassified from accumulated other comprehensive (loss) income(0.2)0.2 — — 
Net current period other comprehensive income0.7 0.2 2.5 3.4 
Ending balance$0.2 $(6.5)$(356.0)$(362.3)

Six Months Ended June 30, 2021(a)
Gains and
(Losses) on
Cash Flow
Hedges		Defined
Benefit
Pension		Foreign
Currency		Total
Beginning balance$0.2 $(9.4)$(294.6)$(303.8)
Other comprehensive income before reclassifications(b)
3.1 — 6.0 9.1 
Amounts reclassified from accumulated other comprehensive (loss) income(2.0)0.5 — (1.5)
Net current period other comprehensive (loss) income1.1 0.5 6.0 7.6 
Ending balance$1.3 $(8.9)$(288.6)$(296.2)
Six Months Ended June 30, 2020(a)
Gains and
(Losses) on
Cash Flow
Hedges		Defined
Benefit
Pension		Foreign
Currency		Total
Beginning balance$(0.6)$(6.9)$(184.7)$(192.2)
Other comprehensive income (loss) before reclassifications(b)
3.6 — (171.3)(167.7)
Amounts reclassified from accumulated other comprehensive (loss) income(2.8)0.4 — (2.4)
Net current period other comprehensive income (loss)0.8 0.4 (171.3)(170.1)
Ending balance$0.2 $(6.5)$(356.0)$(362.3)
(a)With the exception of the CTA, for which no tax effect is recorded, the changes in the components of AOCL presented in the tables above are reflected net of applicable income taxes.
(b)The Company recorded foreign exchange income (loss) of $0.7 million and $(18.5) million in the three and six months ended June 30, 2021, respectively, and $(14.4) million and $(89.9) million in the three and six months ended June 30, 2020, respectively, in AOCL related to intercompany notes which were deemed to be of a long-term investment nature.
Summary of Reclassifications out of Accumulated Other Comprehensive Income
The amounts reclassified from AOCL to expense (income) for the three and six months ended June 30, 2021 and 2020, are shown below (in millions):
Amount Reclassified from AOCL
 Three Months Ended
June 30,		Six Months Ended
June 30,		Line Item Impacted in the
Consolidated Statements of Operations
2021202020212020
Losses on cash flow hedges:
Natural gas instruments$(0.3)$(0.3)$(0.5)$(0.6)Product cost
Foreign currency contracts— — (2.5)(3.6)Interest expense
Income tax expense0.1 0.1 1.0 1.4 
Reclassifications, net of income taxes(0.2)(0.2)(2.0)(2.8)
Amortization of defined benefit pension: 
Amortization of loss0.4 0.2 0.7 0.4 Product cost
Income tax benefit(0.1)— (0.2)— 
Reclassifications, net of income taxes0.3 0.2 0.5 0.4  
Total reclassifications, net of income taxes$0.1 $— $(1.5)$(2.4)