Divestitures Divestitures (Details) - USD ($) $ in Millions			3 Months Ended								12 Months Ended
		Nov. 10, 2019	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	Nov. 08, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Working capital adjustment			$ 6.9								$ 6.9
TexStar Settlement		$ 1.0
TexStar Current Liability			38.1								38.1
Gain (Loss) on sale of business, net											(8.7)	$ 4.8	$ 236.0
Purchase Commitment, Remaining Minimum Amount Committed	[1]		27.7								27.7
Increase in Other Noncurrent Liabilities											19.6
Sales			774.8	$ 929.6	$ 896.9	$ 851.3	$ 848.0	$ 953.5	$ 945.5	$ 750.5	3,452.6	3,497.5	3,763.8
Gross Profit			90.8	$ 117.8	$ 107.1	$ 136.0	95.8	$ 104.3	$ 123.4	$ 113.2	451.7	436.7	498.2
Net income (loss) before income taxes											0.0	(4.1)	(73.5)
San Antonio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Date		Nov. 10, 2019
Total consideration		$ 59.1
Base price		$ 63.0
Sales											403.4	444.2	347.1
Gross Profit											16.2	(4.5)	(7.3)
Net income (loss) before income taxes											(3.9)	(23.7)	(168.7)
Superior
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Date		Nov. 08, 2017
Total consideration														$ 533.1
Base price														435.0
Working capital adjustment														$ (98.1)
Sales											0.0	0.0	669.1
Gross Profit											0.0	0.0	110.0
Net income (loss) before income taxes											0.0	0.0	$ 99.3
Initial | San Antonio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Working capital adjustment		$ 3.9
Final | San Antonio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Working capital adjustment		$ 6.9					$ 0.0					$ 0.0
Present Value [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase Commitment, Remaining Minimum Amount Committed			$ 21.1								$ 21.1

[1] As of December 31, 2019, the estimated minimum payments for the unconditional purchase commitments have been accrued and are included in other current liabilities and other long-term liabilities in the consolidated balance sheets.