Retirement and Deferred Compensation Plans - Schedule of Changes in Fair Value of Pension Assets Measured Using Level 3 Inputs (Details) - Pension plans - Common contractual funds and insurance contracts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, beginning of year	$ 153.9	$ 108.8
Actual return on plan assets	30.5	4.2
Acquisitions	27.6
Transfers		46.2
Purchases, sales and settlements, net	2.5	(0.3)
Currency exchange rate changes	0.3	(5.0)
Fair value of plan assets, end of year	$ 214.8	$ 153.9