Employee Benefit Plans - Estimated Benefit Payments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
2014	$ 10.4
2015	10.6
2016	10.9
2017	11.0
2018	11.2
2019-2023	60.1
Non-qualified Plan Benefits
Defined Benefit Plan Disclosure [Line Items]
2014	0.1
2015	0.7
2016	3.5
2017	0.1
2018	1.0
2019-2023	0.5
Other Post-retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
2014	0.8
2015	0.8
2016	0.8
2017	0.8
2018	0.7
2019-2023	$ 2.5