Employee Retirement Plans (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Obligations and Funded Status
Accumulated Benefit Obligations	$ 442.5	$ 364.8
Projected Benefit Obligations:
Beginning of year	364.8	335.8
Service cost	0.9	0.8	0.9
Interest	19.4	19.6	18.7
Benefits paid	(13.3)	(14.7)
Actuarial loss	70.7	23.3
End of year	442.5	364.8	335.8
Plans' Assets:
Beginning of year	290.6	291.1
Actual return on assets	45.5	(1.2)
Employer contributions	17.3	15.4
Benefits paid	(13.3)	(14.7)
End of year	340.1	290.6	291.1
Consolidated Balance Sheet Components:
Funded status	$ (102.4)	$ (74.2)
Percent of projected benefit obligations funded	76.90%	79.70%