COMMITMENTS AND CONTINGENCIES - Narrative (Details) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 CAD ($)
Loss Contingencies [Line Items]
Eminent domain expenses		$ 0.7
Eminent domain expense reimbursement	$ 5.3
Eagle Rock Materials Ltd., Royalties And Interest
Loss Contingencies [Line Items]
Amount for which the company and its subsidiaries are contingently liable			$ 4.0
Self-insured claims
Loss Contingencies [Line Items]
Amount accrued for self-insurance claims	23.3	$ 20.4
Performance bonds
Loss Contingencies [Line Items]
Amount for which the company and its subsidiaries are contingently liable	14.4
Minimum | Workers' Compensation Insurance And General Liability
Loss Contingencies [Line Items]
Deductible retentions per occurrence	1.0
Minimum | Automobile Insurance
Loss Contingencies [Line Items]
Deductible retentions per occurrence	2.0
Maximum | Workers' Compensation Insurance And General Liability
Loss Contingencies [Line Items]
Deductible retentions per occurrence	2.0
Maximum | Automobile Insurance
Loss Contingencies [Line Items]
Deductible retentions per occurrence	$ 10.0