ACQUISITIONS (Details) $ / shares in Units, $ in Millions				3 Months Ended				12 Months Ended			132 Months Ended
	Aug. 01, 2018 USD ($) shares	Jul. 01, 2018 USD ($) shares	Jun. 06, 2018 USD ($) $ / shares shares	Dec. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) item
ACQUISITIONS
Number of open-deck trucking companies acquired | item											20
Common stock issued in acquisitions						$ 19.7				$ 19.7	$ 19.7
Payment of contingent consideration								$ 7.6
Revenue								1,454.1	$ 1,737.0	1,613.1
Net income (loss)								6.2	(307.4)	(5.2)
Allocation of the purchase price paid to the fair values of the net assets
Goodwill				$ 140.1		258.4		140.1	139.9	258.4	258.4
Amortization of intangible assets								7.2	14.3	16.7
Accumulated amortization				67.8				67.8	60.6
Non-competition agreements
Allocation of the purchase price paid to the fair values of the net assets
Accumulated amortization				19.7				19.7	18.4
Customer relationships
Allocation of the purchase price paid to the fair values of the net assets
Accumulated amortization				48.1				$ 48.1	$ 42.2
Leavitt's
ACQUISITIONS
Voting interest acquired (as a percent)	100.00%
Total consideration paid	$ 14.9
Allocation of the purchase price paid to the fair values of the net assets
Accounts receivable						1.9				1.9	1.9
Parts supplies						0.1				0.1	0.1
Other current assets						0.4				0.4	0.4
Property and equipment						8.5				8.5	8.5
Goodwill						5.1				5.1	5.1
Intangible assets						3.6				3.6	3.6
Accounts payable and other liabilities						(4.9)				(4.9)	(4.9)
Total						14.7				14.7	14.7
Builders
ACQUISITIONS
Voting interest acquired (as a percent)	100.00%
Total consideration paid	$ 36.3
Cash payments for business consideration	$ 30.0
Number of shares transferred | shares	399,530
Common stock issued in acquisitions	$ 3.4
Outstanding debt assumed	2.9
Allocation of the purchase price paid to the fair values of the net assets
Accounts receivable						8.4				8.4	8.4
Parts supplies						0.3				0.3	0.3
Other current assets						1.5				1.5	1.5
Property and equipment						29.4				29.4	29.4
Goodwill						14.7				14.7	14.7
Intangible assets	13.1					10.6				10.6	10.6
Other non-current assets						0.5				0.5	0.5
Deferred tax liability						(9.2)				(9.2)	(9.2)
Accounts payable and other liabilities						(19.9)				(19.9)	(19.9)
Total						36.3				36.3	36.3
Provisional intangible assets										2.5
Transaction expenses incurred, not deductible for taxes purposes	0.2
Amortization expense adjustment						0.2
Previous quarter amortization expense							$ 0.1
Increase (decrease) in goodwill										0.4
Increase (decrease) in deferred tax liability										0.4
Builders | Non-competition agreements
Allocation of the purchase price paid to the fair values of the net assets
Finite lived intangibles						0.5				0.5	0.5
Builders | Customer relationships
Allocation of the purchase price paid to the fair values of the net assets
Finite lived intangibles						5.1				5.1	5.1
Builders | Trade names
Allocation of the purchase price paid to the fair values of the net assets
Finite lived intangibles						5.0				5.0	5.0
Kelsey Trail
ACQUISITIONS
Voting interest acquired (as a percent)		100.00%
Total consideration paid		$ 6.2
Cash payments for business consideration		$ 5.3
Number of shares transferred | shares		95,859
Common stock issued in acquisitions		$ 0.9
Allocation of the purchase price paid to the fair values of the net assets
Accounts receivable						2.3				2.3	2.3
Other current assets						0.4				0.4	0.4
Property and equipment						9.2				9.2	9.2
Goodwill						3.3				3.3	3.3
Intangible assets		1.9				1.5				1.5	1.5
Deferred tax liability						(2.7)				(2.7)	(2.7)
Accounts payable and other liabilities						(8.0)				(8.0)	(8.0)
Total						6.0				6.0	6.0
Indefinite lived intangibles						1.6				1.6	1.6
Transaction expenses incurred, not deductible for taxes purposes		$ 0.1
Increase (decrease) in goodwill					$ (0.9)	2.5				0.3
Increase (decrease) in deferred tax liability					(0.9)	2.5
Kelsey Trail | Non-competition agreements
Allocation of the purchase price paid to the fair values of the net assets
Finite lived intangibles						0.1				0.1	0.1
Kelsey Trail | Trade names
Allocation of the purchase price paid to the fair values of the net assets
Finite lived intangibles						1.5				1.5	1.5
Aveda
ACQUISITIONS
Total consideration paid			$ 118.7
Cash payments for business consideration			$ 27.3
Number of shares transferred | shares			1,612,979
Common stock issued in acquisitions			$ 15.4
Payment of contingent consideration				7.2
Gain resulting from arbitration settlement				$ 13.7
Outstanding debt assumed			54.8
Allocation of the purchase price paid to the fair values of the net assets
Accounts receivable						37.3				37.3	37.3
Other current assets						2.5				2.5	2.5
Property and equipment						89.8				89.8	89.8
Goodwill						7.7				7.7	7.7
Intangible assets			$ 9.0			15.0				15.0	15.0
Deferred tax liability						(6.7)				(6.7)	(6.7)
Accounts payable and other liabilities						(30.0)				(30.0)	(30.0)
Total						115.6				115.6	115.6
Cash per common share | $ / shares			$ 0.45
Finite lived intangibles						15.0				15.0	15.0
Provisional intangible assets										6.1
Transaction expenses incurred, not deductible for taxes purposes			$ 1.1
Increase (decrease) in goodwill					0.7	0.7				4.7
Increase (decrease) in deferred tax liability					$ 0.7	0.7				4.7
Aveda | Non-competition agreements
Allocation of the purchase price paid to the fair values of the net assets
Finite lived intangibles						1.5				1.5	1.5
Aveda | Customer relationships
Allocation of the purchase price paid to the fair values of the net assets
Finite lived intangibles						7.2				7.2	7.2
Aveda | Trade names
Allocation of the purchase price paid to the fair values of the net assets
Finite lived intangibles						6.3				6.3	6.3
Fair Value, Nonrecurring [Member] | Leavitt's
ACQUISITIONS
Finite-lived Intangible Assets, Fair Value Disclosure	5.2
Allocation of the purchase price paid to the fair values of the net assets
Intangible assets						3.6				3.6	3.6
Increase (decrease) in intangible assets due to valuation										1.6
Tax deductible transaction expenses	$ 0.3
Fair Value, Nonrecurring [Member] | Leavitt's | Non-competition agreements
ACQUISITIONS
Finite-lived Intangible Assets, Fair Value Disclosure						0.5				0.5	0.5
Fair Value, Nonrecurring [Member] | Leavitt's | Customer relationships
ACQUISITIONS
Finite-lived Intangible Assets, Fair Value Disclosure						1.3				1.3	1.3
Fair Value, Nonrecurring [Member] | Leavitt's | Trade names
ACQUISITIONS
Finite-lived Intangible Assets, Fair Value Disclosure						$ 1.8				$ 1.8	$ 1.8