Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Plan, Defined Benefit [Member]
Components of Net Periodic Benefit Cost
Service cost - benefits earned during the period	$ 2.3	$ 1.9
Interest cost on projected benefit obligation	7.0	6.7
Expected return on plan assets	(10.6)	(10.8)
Amortization of prior service cost	0.3	0.2
Recognized actuarial net (gain) or loss	2.6	4.2
Net periodic benefit (income) cost	1.6	2.2
Other Postretirement Benefit Plan, Defined Benefit [Member]
Components of Net Periodic Benefit Cost
Service cost - benefits earned during the period	0.0	0.0
Interest cost on projected benefit obligation	0.0	0.0
Expected return on plan assets	0.0	0.0
Amortization of prior service cost	0.0	0.0
Recognized actuarial net (gain) or loss	(0.3)	(0.3)
Net periodic benefit (income) cost	(0.3)	(0.3)
Bemis Investment Profit Sharing Plan and Other Defined Contribution Plans [Member]
Components of Net Periodic Benefit Cost
Defined contribution benefits plans	$ 6.6	$ 7.1