Employee Benefits Schedule of Net Periodic Benefit Cost and Other Comprehensive Income for Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current period prior service cost	[1]	$ 0.0	$ 0.6	$ 0.0
Pension Plan and SERP [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1.2	2.1	2.6
Interest cost		5.2	4.9	5.3
Expected return on plan assets		(5.6)	(5.7)	(5.1)
Curtailment loss		0.0	11.2	9.3
Special termination benefits		0.0	0.0	1.9
Settlements		0.0	0.0	0.7
Amortization of prior service costs		1.1	1.7	4.7
Amortization of actuarial loss		0.8	0.5	0.8
Periodic expense		2.7	14.7	20.2
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current period prior service cost		0.0	0.9	0.0
Current period actuarial (gain) loss		8.5	2.2	21.5
Amortization of prior service cost		(1.1)	(12.9)	(14.0)
Amortization of actuarial gain (loss)		(0.8)	(0.5)	(0.8)
Loss on curtailment in current period		0.0	(7.1)
Loss on curtailment in current period		0.0	(7.1)	(8.2)
Settlements		0.0	0.0	0.7
Total amount recognized in accumulated other comprehensive income		0.0	0.0	(0.7)
Other Comprehensive Income (Loss), before Tax		6.6	(17.4)	(2.2)
Medical Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		0.0	0.0	0.0
Interest cost		0.2	0.2	0.3
Expected return on plan assets		0.0	0.0	0.0
Curtailment loss		0.0	0.0	1.4
Special termination benefits		0.0	0.0	0.0
Settlements		0.0	0.0	0.0
Amortization of prior service costs		0.2	0.2	0.3
Amortization of actuarial loss		0.0	0.0	0.0
Periodic expense		0.4	0.4	2.0
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current period prior service cost		0.0	0.0	0.0
Current period actuarial (gain) loss		0.4	(1.4)	0.6
Amortization of prior service cost		(0.2)	(0.2)	(1.7)
Amortization of actuarial gain (loss)		0.0	0.0	0.0
Loss on curtailment in current period		0.0	0.0
Loss on curtailment in current period		0.0	0.0	(0.2)
Settlements		0.0	0.0	0.0
Total amount recognized in accumulated other comprehensive income		0.0	0.0	0.0
Other Comprehensive Income (Loss), before Tax		$ 0.2	$ (1.6)	$ (1.3)

[1] Presented net of income tax benefit of $0.3 million for the year ended December 31, 2015.