Employee Separation and Restructuring Costs Employee Separation and Restructuring Costs (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended		24 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 94.1	$ 52.0
Spartech [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs				36.7
Restructuring Reserve, Accrual Adjustment		2.7	15.1	2.7	0
Restructuring and Related Cost, Expected Cost	15.0
Restructuring charges		59.7	44.1	103.8
Payments for Restructuring		(44.8)	(15.4)
Restructuring Reserve, Settled without Cash		(27.3)	(13.6)
Severance Costs				26.2
Brazil [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Accrual Adjustment		1.1	0	1.1
Restructuring charges		17.0
Payments for Restructuring		(5.2)
Restructuring Reserve, Settled without Cash		(10.7)
Europe
Restructuring Cost and Reserve [Line Items]
Restructuring charges		17.4
Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		54.0	16.1
Selling and administrative expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges		40.1	35.9
Assets [Member] | Spartech [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Accrual Adjustment		0	0	0	0
Restructuring charges		27.3	13.6	40.9
Payments for Restructuring		0	0
Restructuring Reserve, Settled without Cash		(27.3)	(13.6)
Assets [Member] | Brazil [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Accrual Adjustment		0	0	0
Restructuring charges		10.7
Payments for Restructuring		0
Restructuring Reserve, Settled without Cash		(10.7)
Employee Severance [Member] | Spartech [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Accrual Adjustment		2.7	15.1	2.7	0
Restructuring charges		5.1	21.1
Payments for Restructuring		(17.5)	(6.0)
Restructuring Reserve, Settled without Cash		0	0
Employee Severance [Member] | Brazil [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Accrual Adjustment		1.1	0	1.1
Restructuring charges		2.9
Payments for Restructuring		(1.8)
Restructuring Reserve, Settled without Cash		0
Other Restructuring [Member] | Spartech [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Accrual Adjustment		0	0	0	0
Restructuring charges		27.3	9.4
Payments for Restructuring		(27.3)	(9.4)
Restructuring Reserve, Settled without Cash		0	0
Other Restructuring [Member] | Brazil [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Accrual Adjustment		0	0	0
Restructuring charges		3.4
Payments for Restructuring		(3.4)
Restructuring Reserve, Settled without Cash		$ 0