Employee Retirement Plans (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligations	$ 459.6	$ 445.3
Projected Benefit Obligations:
Beginning of year	445.3	473.9
Service cost	0.4	0.5	$ 0.5
Interest	20.8	20.0	20.2
Benefits paid	(18.1)	(17.3)
Actuarial (gain)/loss	11.2	(31.8)
End of year	459.6	445.3	473.9
Plans' Assets:
Beginning of year	422.8	434.5
Actual return on assets	33.1	(10.6)
Employer contributions	4.7	16.2
Benefits paid	(18.1)	(17.3)
End of year	442.5	422.8	$ 434.5
Consolidated Balance Sheet Components:
Net funded status	$ (17.1)	$ (22.5)
Percent of projected benefit obligations funded	96.30%	94.90%
Other assets
Consolidated Balance Sheet Components:
Defined Benefit Plan, Amounts Recognized in Balance Sheet	$ 5.1	$ 3.5
Accrued liabilities
Consolidated Balance Sheet Components:
Defined Benefit Plan, Amounts Recognized in Balance Sheet	$ (22.2)	$ (26.0)