Income Taxes - Summary of Company's Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Allowance for doubtful accounts	$ 1.2	$ 1.2
Insurance reserve	12.9	12.5
Net operating loss	115.5	100.7
Accrued bonus and vacation	4.7	4.1
Stock compensation	5.2	6.0
Tax credits	1.9	1.7
Other	9.9	12.0
Total deferred tax assets	151.3	138.2
Valuation allowance	(23.0)	(15.4)
Deferred tax assets less valuation allowance	128.3	122.8
Deferred tax liabilities
Fixed asset basis	(101.2)	(82.9)
Intangible basis	(69.9)	(70.9)
Landfill and environmental remediation liabilities	(41.1)	(52.3)
Other	(4.6)	(7.8)
Deferred tax liabilities	(216.8)	(213.9)
Net deferred tax liability	$ (88.5)	$ (91.1)