Financial Instruments, Risk Management and Fair Value Measurements - Recurring Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Assets
Investments in deferred compensation plan	$ 2.0	$ 2.0	$ 1.6
Total Assets	2.0	2.0	1.6
Liabilities
Deferred compensation plan obligation	2.7	2.7	2.5
Total Liabilities	2.7	2.7	2.5
Level 1
Assets
Investments in deferred compensation plan	2.0	2.0	1.6
Total Assets	2.0	2.0	1.6
Liabilities
Deferred compensation plan obligation	2.7	2.7	2.5
Total Liabilities	2.7	2.7	2.5
Level 2
Assets
Investments in deferred compensation plan	0.0	0.0	0.0
Total Assets	0.0	0.0	0.0
Liabilities
Deferred compensation plan obligation	0.0	0.0	0.0
Total Liabilities	0.0	0.0	0.0
Level 3
Assets
Investments in deferred compensation plan	0.0	0.0	0.0
Total Assets	0.0	0.0	0.0
Liabilities
Deferred compensation plan obligation	0.0	0.0	0.0
Total Liabilities	0.0	0.0	$ 0.0
Selling, General and Administrative Expenses
Liabilities
Mark-to-market gain on common stock	$ 0.1	$ 0.2