Derivatives, Hedging Programs and Other Financial Instruments, Narrative (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Cost of products sold, excluding depreciation and amortization and other items	$ 298,000,000.0	$ 298,600,000	$ 303,500,000	$ 315,100,000	$ 317,300,000	$ 323,300,000	$ 343,400,000	$ 316,700,000	$ 1,215,200,000	[1]	$ 1,300,700,000	[1]	$ 1,085,900,000	[1]
Derivative, Net Liability Position, Aggregate Fair Value	7,200,000				$ 12,600,000				7,200,000		12,600,000
Margin deposits with counterparties	0								0
Customer Deposits, Current	$ 200,000								$ 200,000
Debt Instrument, Term									12 months
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months									$ (5,500,000)
Scenario, Forecast | Natural Gas Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage															77.00%	83.00%	83.00%	78.00%	80.00%
Scenario, Forecast | Electricity [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage																	9.00%	55.00%	55.00%
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
Derivative [Line Items]
OCI, before Reclassifications, before Tax, Attributable to Parent									$ (9,500,000)		$ (21,200,000)		$ 1,800,000

[1] See Note 8 for discussion of our adoption of ASU 2017-12 (as defined in Note 1) in 2018 and the related reclassification of amounts in 2017 that were presented in the Statements of Consolidated Income within Unrealized (gain) loss on derivative instruments and are now presented within Cost of products sold, excluding depreciation and amortization and other items ("Cost of products sold").