Employee Benefits Schedule of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Pension Plan and SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost		$ 0.1	$ 0.4	$ 0.4	$ 0.6
Interest cost		1.2	1.4	2.4	2.6
Expected return on plan assets		(1.4)	(1.4)	(2.7)	(2.8)
Amortization of prior service costs	[1]	0.3	0.4	0.6	0.6
Amortization of actuarial losses	[1]	(0.1)	0.3	0.2	0.4
Periodic expense		0.1	1.1	0.9	1.4
Medical Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost		0.1	0.0	0.1	0.1
Amortization of prior service costs	[1]	0.0	0.1	(0.1)	0.1
Periodic expense		$ 0.1	$ 0.1	$ 0.0	$ 0.2

[1] Amortization of prior service costs out of accumulated other comprehensive income are recognized on the Condensed Consolidated Statements of Operations within "Interest and other income (expense)".