INCOME TAXES - Deferred tax assets and liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Accrued expenses	$ 7.4	$ 5.5
Vacation accrual	0.6	0.6
Accounts receivable	0.9	0.8
Net operating losses	24.4	38.6
Deferred start-up costs	1.2	1.3
Stock based compensation	2.0	1.5
Operating lease liabilities	30.3	25.9
Total	66.8	74.2
Valuation allowance	(10.5)	(7.4)
Total deferred tax assets	56.3	66.8
Deferred tax liabilities
Prepaid expenses	(4.8)	(4.7)
481(a) adjustment		(0.9)
Intangible assets	(17.6)	(20.3)
Property and equipment	(75.6)	(87.2)
Right of Use Asset	(28.3)	(23.6)
Total deferred tax liabilities	126.3	136.7
Net deferred tax liability	$ (70.0)	$ (69.9)