Acquisitions (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2022 USD ($) Location	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) Location	Jun. 30, 2021 USD ($)	Apr. 02, 2022 Location State	Dec. 31, 2021 Location	Dec. 01, 2021 Location	Oct. 02, 2021 Location	Sep. 30, 2021 USD ($)
Acquisition [Abstract]
Number of retail locations | Location	96		96
Cash paid for acquisition			$ 326,100
Note payable to seller			1,100
Payment of contingent consideration	$ 15,300		15,300
Issuance of shares of Class A common stock			14,600
Minimum payout due of contingent consideration	5,900		5,900
Maximum payout due of contingent consideration	24,700		24,700
Summary of Assets Acquired and Liabilities Assumed [Abstract]
Goodwill	342,605		342,605						$ 168,491
Consideration transferred	357,200		357,200
Revenue	568,900	$ 404,207	1,347,299	$ 947,901
Income before income tax expense	83,268	63,055	166,778	114,482
Costs related to acquisition	$ 1,200	100	4,900	600
Unaudited Pro Forma Results of Operations [Abstract]
Pro forma revenue		526,136	1,431,881	1,297,780
Pro forma net income		$ 66,648	$ 135,253	$ 129,158
Notes Payable [Member]
Acquisition [Abstract]
Interest rate	4.00%		4.00%
Naples Boat Mart [Member]
Acquisition [Abstract]
Number of stores | Location								1
Norfolk Marine [Member]
Acquisition [Abstract]
Number of stores | Location							1
T-H Marine [Member]
Summary of Assets Acquired and Liabilities Assumed [Abstract]
Accounts receivable	$ 8,955		$ 8,955
Inventories	19,856		19,856
Prepaid expenses	1,547		1,547
Property and equipment	3,896		3,896
Deposits	0		0
Operating lease right-of-use assets	5,960		5,960
Identifiable intangible assets	105,500		105,500
Goodwill	51,694		51,694
Accounts payable	(3,876)		(3,876)
Accrued expenses	(1,697)		(1,697)
Customer deposits	(394)		(394)
Operating lease liabilities	(5,960)		(5,960)
Aggregate acquisition date fair value	185,481		185,481
Consideration transferred	185,481		185,481
Fair value of non-controlling interests	0		0
Quality Boats [Member]
Acquisition [Abstract]
Number of stores | Location						3
Percentage of economic interest retained by sellers						20.00%
Percentage of remaining economic interest						20.00%
Summary of Assets Acquired and Liabilities Assumed [Abstract]
Accounts receivable	0		0
Inventories	5,937		5,937
Prepaid expenses	47		47
Property and equipment	803		803
Deposits	0		0
Operating lease right-of-use assets	11,877		11,877
Identifiable intangible assets	31,700		31,700
Goodwill	78,682		78,682
Accounts payable	0		0
Accrued expenses	0		0
Customer deposits	(5,047)		(5,047)
Operating lease liabilities	(11,877)		(11,877)
Aggregate acquisition date fair value	112,122		112,122
Consideration transferred	92,811		92,811
Fair value of non-controlling interests	19,311		19,311
Denison Yachting [Member]
Acquisition [Abstract]
Number of retail locations | Location					20
Number of states | State					7
Summary of Assets Acquired and Liabilities Assumed [Abstract]
Accounts receivable	654		654
Inventories	1,981		1,981
Prepaid expenses	2,053		2,053
Property and equipment	293		293
Deposits	126		126
Operating lease right-of-use assets	1,221		1,221
Identifiable intangible assets	16,600		16,600
Goodwill	29,144		29,144
Accounts payable	(80)		(80)
Accrued expenses	(252)		(252)
Customer deposits	(5,524)		(5,524)
Operating lease liabilities	(1,221)		(1,221)
Aggregate acquisition date fair value	44,995		44,995
Consideration transferred	44,995		44,995
Fair value of non-controlling interests	0		0
Other Acquisitions [Member]
Summary of Assets Acquired and Liabilities Assumed [Abstract]
Accounts receivable	1,122		1,122
Inventories	9,618		9,618
Prepaid expenses	357		357
Property and equipment	1,227		1,227
Deposits	13		13
Operating lease right-of-use assets	7,375		7,375
Identifiable intangible assets	11,276		11,276
Goodwill	14,594		14,594
Accounts payable	(471)		(471)
Accrued expenses	(553)		(553)
Customer deposits	(3,307)		(3,307)
Operating lease liabilities	(7,375)		(7,375)
Aggregate acquisition date fair value	33,876		33,876
Consideration transferred	33,876		33,876
Fair value of non-controlling interests	0		0
Total Acquisitions [Member]
Summary of Assets Acquired and Liabilities Assumed [Abstract]
Accounts receivable	10,731		10,731
Inventories	37,392		37,392
Prepaid expenses	4,004		4,004
Property and equipment	6,219		6,219
Deposits	139		139
Operating lease right-of-use assets	26,433		26,433
Identifiable intangible assets	165,076		165,076
Goodwill	174,114		174,114
Accounts payable	(4,427)		(4,427)
Accrued expenses	(2,502)		(2,502)
Customer deposits	(14,272)		(14,272)
Operating lease liabilities	(26,433)		(26,433)
Aggregate acquisition date fair value	376,474		376,474
Consideration transferred	357,163		357,163
Fair value of non-controlling interests	19,311		19,311
Revenue	91,800		178,500
Income before income tax expense	$ 16,600		$ 29,900