Non-Qualified Retirement, Savings and Investment Plans (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) plan shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)
Retirement Benefits [Abstract]
Number of non-qualified retirement savings and investment plans | plan	2
Deferred compensation liability, current and long-term	$ 32.1	$ 26.1
Number of Deferred Compensation Plans | plan	2
Increase (decrease) in compensation expense	$ 5.3	(0.7)	$ 3.7
Deferred compensation plan assets	27.1	21.3
Restricted investments, current	2.1
Investment gains (losses)	$ 4.9	$ (1.3)	$ 3.2
Deferred compensation arrangement with individual, shares issued (in shares) | shares	0	0