Retirement and Deferred Compensation Plans - Reconciliation of Changes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension plans
Change in Benefit Obligation
Service cost	$ 10.9	$ 10.1	$ 8.0
Interest cost	11.6	10.6	11.8
Pension plans | United States Plans
Change in Benefit Obligation
Benefit obligation, beginning of year	53.7	53.1
Service cost	0.0	0.0
Interest cost	1.6	1.7
Transfers	0.0	0.0
Actuarial (gain) loss	(2.0)	3.0
Plan participant contributions	0.0	0.0
Benefits paid	(4.4)	(4.1)
Currency exchange rate changes	0.0	0.0
Benefit obligation, end of year	48.9	53.7	53.1
Change in Plan Assets
Fair value of plan assets, beginning of year	38.7	37.3
Actual return on plan assets	(0.7)	3.0
Transfers	0.0	0.0
Plan participant contributions	0.0	0.0
Company contributions	2.5	2.5
Benefits paid	(4.4)	(4.1)
Currency exchange rate changes	0.0	0.0
Fair value of plan assets, end of year	36.1	38.7	37.3
Funded Status at End of Year
Funded status, end of year	(12.8)	(15.0)
Amounts Recognized
Noncurrent assets	15.0	15.3
Current liabilities	(2.5)	(2.5)
Noncurrent liabilities	(25.3)	(27.8)
Net amount recognized	(12.8)	(15.0)
Pension plans | Non-United States Plans
Change in Benefit Obligation
Benefit obligation, beginning of year	489.5	416.0
Service cost	10.9	10.1
Interest cost	10.0	8.9
Transfers	1.2	9.3
Actuarial (gain) loss	(28.0)	1.0
Plan participant contributions	0.2	0.2
Benefits paid	(10.5)	(9.5)
Currency exchange rate changes	(23.3)	53.5
Benefit obligation, end of year	450.0	489.5	416.0
Change in Plan Assets
Fair value of plan assets, beginning of year	376.7	324.5
Actual return on plan assets	(2.4)	13.4
Transfers	(0.3)	1.8
Plan participant contributions	0.2	0.2
Company contributions	9.2	7.9
Benefits paid	(10.5)	(9.5)
Currency exchange rate changes	(18.8)	38.4
Fair value of plan assets, end of year	354.1	376.7	324.5
Funded Status at End of Year
Funded status, end of year	(95.9)	(112.8)
Amounts Recognized
Noncurrent assets	46.9	36.8
Current liabilities	(0.5)	(0.4)
Noncurrent liabilities	(142.3)	(149.2)
Net amount recognized	(95.9)	(112.8)
Retiree health care plan
Change in Benefit Obligation
Benefit obligation, beginning of year	14.9	15.6
Interest cost	0.5	0.6	0.7
Actuarial (gain) loss	(0.5)	(0.3)
Benefits paid	(1.2)	(1.0)
Benefit obligation, end of year	13.7	14.9	$ 15.6
Funded Status at End of Year
Funded status, end of year	(13.7)	(14.9)
Amounts Recognized
Current liabilities	(1.1)	(1.2)
Noncurrent liabilities	(12.6)	(13.7)
Net amount recognized	$ (13.7)	$ (14.9)