Employee Benefit Plans (Schedule of Underfunded Plan Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Plan [Member]
Change in benefit obligation:
Benefit obligation, beginning balance	$ 40.4	$ 43.4
Service cost	1.1	1.2	1.7
Interest cost	1.8	1.6	1.8
Change in plan provisions	0	0
Benefits paid	(1.2)	(1.2)
Actuarial (gain) loss	7.6	(4.6)
Benefit obligation, ending balance	49.7	40.4	43.4
Change in fair value of plan assets:
Plan assets, beginning balance	0	0
Employer contribution	1.2	1.2
Benefits paid	(1.2)	(1.2)
Plan assets, ending balance	0	0	0
Underfunded status, end of year	(49.7)	(40.4)
Other Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning balance	24.1	26.9
Service cost	0.3	0.4	0.4
Interest cost	1.1	1.0	1.1
Change in plan provisions	0	(0.6)
Benefits paid	(1.1)	(0.9)
Actuarial (gain) loss	4.4	(2.7)
Benefit obligation, ending balance	28.8	24.1	26.9
Change in fair value of plan assets:
Plan assets, beginning balance	0	0
Employer contribution	1.1	0.9
Benefits paid	(1.1)	(0.9)
Plan assets, ending balance	0	0	0
Underfunded status, end of year	$ (28.8)	$ (24.1)