Description of Business and Summary of Significant Accounting Policies Goodwill Table (Details) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
	Feb. 28, 2017	Aug. 31, 2018	Feb. 28, 2019	Feb. 28, 2018	Apr. 18, 2017	Feb. 29, 2016
Goodwill [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	$ 0	$ 9,814,000	$ 25,789,000	$ 0
Goodwill	53,905,000		54,785,000	54,785,000	$ 10,000	$ 53,905,000
Goodwill, Acquired During Period	0		0	880,000
Goodwill, Impairment Loss	0		0	0
Goodwill, Gross	86,068,000		86,948,000	86,948,000
Goodwill, Impaired, Accumulated Impairment Loss	(32,163,000)		(32,163,000)	(32,163,000)
Automotive [Member]
Goodwill [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)			160,000
Goodwill	7,372,000		8,252,000	8,252,000		7,372,000
Goodwill, Acquired During Period	0		0	880,000
Goodwill, Gross	7,372,000		8,252,000	8,252,000
Goodwill, Impaired, Accumulated Impairment Loss	0		0	0
Premium Audio [Member]
Goodwill [Line Items]
Goodwill	46,533,000		46,533,000	46,533,000		$ 46,533,000
Goodwill, Impairment Loss	0		0	0
Goodwill, Gross	78,696,000		78,696,000	78,696,000
Goodwill, Impaired, Accumulated Impairment Loss	$ (32,163,000)		$ (32,163,000)	$ (32,163,000)
Minimum [Member]
Goodwill [Line Items]
Impaired Long-Lived Assets Held and Used, Method for Determining Fair Value			.005
Maximum [Member]
Goodwill [Line Items]
Impaired Long-Lived Assets Held and Used, Method for Determining Fair Value			.07