Employee Benefit Plans - Reconciliation of Pension Plan Investments Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) (USD $) In Millions, unless otherwise specified																12 Months Ended				12 Months Ended						12 Months Ended				12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Pension Benefits	Dec. 31, 2012 Pension Benefits	Dec. 31, 2011 Pension Benefits	Dec. 31, 2013 Real estate partnership interests	Dec. 31, 2012 Real estate partnership interests	Dec. 31, 2013 Private Equity		Dec. 31, 2012 Private Equity		Dec. 31, 2013 Insurance	Dec. 31, 2012 Insurance	Dec. 31, 2013 Significant Un-observable Inputs (Level 3)	Dec. 31, 2012 Significant Un-observable Inputs (Level 3)	Dec. 31, 2013 Significant Un-observable Inputs (Level 3) Pension Benefits	Dec. 31, 2012 Significant Un-observable Inputs (Level 3) Pension Benefits	Dec. 31, 2013 Significant Un-observable Inputs (Level 3) Real estate partnership interests	Dec. 31, 2012 Significant Un-observable Inputs (Level 3) Real estate partnership interests	Dec. 31, 2013 Significant Un-observable Inputs (Level 3) Real estate partnership interests Pension Benefits	Dec. 31, 2012 Significant Un-observable Inputs (Level 3) Real estate partnership interests Pension Benefits	Dec. 31, 2013 Significant Un-observable Inputs (Level 3) Private Equity		Dec. 31, 2012 Significant Un-observable Inputs (Level 3) Private Equity		Dec. 31, 2013 Significant Un-observable Inputs (Level 3) Private Equity Pension Benefits	Dec. 31, 2012 Significant Un-observable Inputs (Level 3) Private Equity Pension Benefits	Dec. 31, 2013 Significant Un-observable Inputs (Level 3) Insurance	Dec. 31, 2012 Significant Un-observable Inputs (Level 3) Insurance	Dec. 31, 2013 Significant Un-observable Inputs (Level 3) Insurance Pension Benefits	Dec. 31, 2012 Significant Un-observable Inputs (Level 3) Insurance Pension Benefits	Dec. 31, 2013 Significant Un-observable Inputs (Level 3) Limited Partner [Member] Pension Benefits	Dec. 31, 2011 Significant Un-observable Inputs (Level 3) Limited Partner [Member] Pension Benefits
Change in plan assets [Roll Forward]
Fair value of plan assets at beginning of year	$ 153.4	$ 142.3	$ 153.4	$ 142.3	$ 130.8	$ 7.5	$ 7.8	$ 0.3	[1]	$ 0.7	[1]	$ 1.0	$ 0.9	$ 15.2	$ 9.4	$ 9.4	$ 8.9	$ 7.5	$ 7.8	$ 7.8	$ 7.4	$ 0.3	[1]	$ 0.7	[1]	$ 0.7	$ 0.8	$ 1.0	$ 0.9	$ 0.9	$ 0.7	$ 0	$ 0
Actual return on plan assets [Abstract]
Assets held at the reporting date																1.3	0.7			1.1	0.7					(0.2)				0.1		0.3
Assets sold during the period																0.4	0.6			0.3	0.3					0.1	0.3
Purchases, sales and settlements																4.1	(0.8)			(1.7)	(0.6)					(0.3)	(0.4)				0.2	6.1
Fair value of plan assets at end of year	$ 153.4	$ 142.3	$ 153.4	$ 142.3	$ 130.8	$ 7.5	$ 7.8	$ 0.3	[1]	$ 0.7	[1]	$ 1.0	$ 0.9	$ 15.2	$ 9.4	$ 15.2	$ 9.4	$ 7.5	$ 7.8	$ 7.5	$ 7.8	$ 0.3	[1]	$ 0.7	[1]	$ 0.3	$ 0.7	$ 1.0	$ 0.9	$ 1.0	$ 0.9	$ 6.4	$ 0

[1] This category represents private equity funds that invest principally in U.S. technology companies.