Employee Separation And Restructuring Costs - Narrative (Details)	3 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2015 facility	Mar. 31, 2016 USD ($)	Dec. 31, 2013 office facility
Restructuring Cost and Reserve [Line Items]
Charged to expense	$ 7,100,000	$ 10,600,000
Accelerated depreciation costs	2,800,000	100,000
Selling, General and Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Charged to expense	4,400,000	2,700,000
Cost of Sales
Restructuring Cost and Reserve [Line Items]
Charged to expense	2,700,000	7,900,000
DSS Manufacturing Facility Closure | Facility Closing
Restructuring Cost and Reserve [Line Items]
Number of facilities closed | facility			2
Charged to expense	5,100,000			$ 22,200,000
Severance costs				8,300,000
Accelerated depreciation costs				8,600,000
Other associated restructuring costs				1,200,000
Expected remaining costs	5,000,000			5,000,000
DSS Manufacturing Facility Closure | Asset and Deprecation Charges
Restructuring Cost and Reserve [Line Items]
Charged to expense				$ 12,700,000
Spartech | Facility Closing
Restructuring Cost and Reserve [Line Items]
Number of facilities closed | facility					7
Charged to expense	$ 0	$ 9,300,000
Spartech | Administrative Office Closing
Restructuring Cost and Reserve [Line Items]
Number of facilities closed | office					1