Financial Instruments, Risk Management and Fair Value Measurements - Recurring Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Mar. 31, 2020
Assets
Investments in deferred compensation plan	$ 1.6	$ 1.6
Total Assets	1.6	1.6
Liabilities
Deferred compensation plan obligation	2.5	2.2
Total Liabilities	2.5	2.2
Level 1
Assets
Investments in deferred compensation plan	1.6	1.6
Total Assets	1.6	1.6
Liabilities
Deferred compensation plan obligation	2.5	2.2
Total Liabilities	2.5	2.2
Level 2
Assets
Investments in deferred compensation plan	0.0	0.0
Total Assets	0.0	0.0
Liabilities
Deferred compensation plan obligation	0.0	0.0
Total Liabilities	0.0	0.0
Level 3
Assets
Investments in deferred compensation plan	0.0	0.0
Total Assets	0.0	0.0
Liabilities
Deferred compensation plan obligation	0.0	0.0
Total Liabilities	0.0	$ 0.0
Selling, General and Administrative Expenses
Liabilities
Mark-to-market gain on common stock	$ 0.3