GOODWILL IMPAIRMENT - Schedule of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 312,818	$ 312,820	$ 312,689	$ 317,691
Accumulated impairment losses, beginning of period	(108,400)	(108,400)	(1,663)	(6,607)
Goodwill, beginning of period	204,418	204,420	311,026	311,084
Impact of divestiture on goodwill				(4,944)
Impact of divestiture on accumulated impairment losses				4,944
Goodwill impairments	0	0	(106,737)
Effects of foreign currency	(67)	(2)	131	(58)
Goodwill, end of period	312,751	312,818	312,820	312,689
Accumulated impairment losses, end of period	(108,400)	(108,400)	(108,400)	(1,663)
Goodwill, end of period	204,351	204,418	204,420	311,026
Commercial Trailer Products
Goodwill [Roll Forward]
Goodwill, beginning of period	4,288	4,288	4,288	4,288
Accumulated impairment losses, beginning of period	(1,663)	(1,663)	(1,663)	(1,663)
Goodwill, beginning of period	2,625	2,625	2,625	2,625
Impact of divestiture on goodwill				0
Impact of divestiture on accumulated impairment losses				0
Goodwill impairments	0	0	0
Effects of foreign currency	0	0	0	0
Goodwill, end of period	4,288	4,288	4,288	4,288
Accumulated impairment losses, end of period	(1,663)	(1,663)	(1,663)	(1,663)
Goodwill, end of period	2,625	2,625	2,625	2,625
Diversified Products
Goodwill [Roll Forward]
Goodwill, beginning of period	140,815	140,817	140,686	145,688
Accumulated impairment losses, beginning of period	(10,971)	(10,971)	0	(4,944)
Goodwill, beginning of period	129,844	129,846	140,686	140,744
Impact of divestiture on goodwill				(4,944)
Impact of divestiture on accumulated impairment losses				4,944
Goodwill impairments	0	0	(10,971)
Effects of foreign currency	(67)	(2)	131	(58)
Goodwill, end of period	140,748	140,815	140,817	140,686
Accumulated impairment losses, end of period	(10,971)	(10,971)	(10,971)	0
Goodwill, end of period	129,777	129,844	129,846	140,686
Final Mile Products
Goodwill [Roll Forward]
Goodwill, beginning of period	167,715	167,715	167,715	167,715
Accumulated impairment losses, beginning of period	(95,766)	(95,766)	0	0
Goodwill, beginning of period	71,949	71,949	167,715	167,715
Impact of divestiture on goodwill				0
Impact of divestiture on accumulated impairment losses				0
Goodwill impairments	0	0	(95,766)
Effects of foreign currency	0	0	0	0
Goodwill, end of period	167,715	167,715	167,715	167,715
Accumulated impairment losses, end of period	(95,766)	(95,766)	(95,766)	0
Goodwill, end of period	$ 71,949	$ 71,949	$ 71,949	$ 167,715