Acquisitions, Goodwill And Other Intangible Assets (Schedule Of Business Acquisitions) (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended	6 Months Ended	9 Months Ended
	Jan. 31, 2020	Dec. 31, 2019	Aug. 31, 2019	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Cash consideration, net of cash acquired						$ 94,909	$ 53,923
Goodwill		$ 351,114		$ 413,068		413,068
Measurement Period Adjustments
Goodwill (not tax deductible)						10,362
Polyplastic
Business Acquisition [Line Items]
Cash consideration, net of cash acquired	$ 95,766
Contingent consideration	2,796
Total fair value of consideration given	98,562
Identifiable intangible assets	63,626
Net tangible assets	15,460
Accrued expenses and other current liabilities	(28,665)
Total fair value of net assets acquired	50,421
Goodwill	$ 48,141
Measurement Period Adjustments
Intangible assets				10,000
CURT
Business Acquisition [Line Items]
Cash consideration, net of cash acquired		337,640				336,587
Accounts receivable		28,611		28,611		28,611
Inventories		88,765		82,117		82,117
Fixed assets		24,036		24,036		24,036
Operating lease right-of-use assets		27,925		27,925		27,925
Other tangible assets		4,060		2,510		2,510
Accounts payable		(18,577)		(18,577)		(18,577)
Current portion of operating lease obligations		(5,360)		(5,360)		(5,360)
Accrued expenses and other current liabilities		(10,002)		(10,002)		(10,002)
Operating lease obligations		(22,565)		(22,565)		(22,565)
Deferred taxes		(31,877)		(30,125)		(30,125)
Total fair value of net assets acquired		234,721		220,175		220,175
Goodwill		102,919		116,412		116,412
Measurement Period Adjustments
Cash consideration, net of cash acquired						(1,053)
Inventories						(6,648)
Other tangible assets						(1,550)
Deferred taxes						1,752
Total fair value of net assets acquired						(14,546)
Goodwill (not tax deductible)						13,493
CURT | Customer Relationships
Business Acquisition [Line Items]
Identifiable intangible assets		112,000		104,200		104,200
Measurement Period Adjustments
Intangible assets						(7,800)
CURT | Tradenames
Business Acquisition [Line Items]
Identifiable intangible assets		37,705		37,405		37,405
Measurement Period Adjustments
Intangible assets						(300)
Lewmar Marine Limited
Business Acquisition [Line Items]
Cash consideration, net of cash acquired					$ 43,224	43,224
Total fair value of consideration given			$ 43,200
Identifiable intangible assets		19,580		21,750		21,750
Net tangible assets		3,286		2,581		2,581
Total fair value of net assets acquired		22,866		24,331		24,331
Goodwill		$ 20,358		$ 18,893		18,893
Measurement Period Adjustments
Intangible assets						2,170
Other tangible assets						(705)
Total fair value of net assets acquired						1,465
Goodwill (not tax deductible)						$ (1,465)