Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 employee	Dec. 31, 2011	Dec. 31, 2010
Compensation and Retirement Disclosure [Abstract]
Number of employees sponsored by defined benefit pension plans	14,000
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	$ 1,166.2	$ 1,077.1
Service cost	3.9	3.6	3.6
Interest cost	59.3	61.2	60.1
Benefits paid	(63.1)	(57.7)
Actuarial loss	192.1	91.5
Expenses paid from assets	(12.7)	(9.5)
Benefit obligation at year end	1,345.7	1,166.2	1,077.1
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at prior year end	727.7	633.7
Actual return on plan assets	72.2	130.9
Employer contributions	75.3	30.3
Benefits paid	(63.1)	(57.7)
Expenses paid from assets	(12.7)	(9.5)
Fair value of plan assets at year end	799.4	727.7	633.7
Funded status at year end	(546.3)	(438.5)
Noncurrent assets	0	1.4
Current liabilities	0.6	3.0
Noncurrent liabilities	545.7	436.9
Net actuarial loss	511.8	350.3
Prior service cost	0	0
Total	511.8	350.3
Unrecognized actuarial losses net of tax	418.4
Actuarial loss included in accumulated other comprehensive income and expected to be recognized next year	$ 14.9