Segment Reporting - Net Income By Segment (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2024	Sep. 30, 2023	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenue:
Total income	$ 49,453,000		$ 51,285,000	$ 100,265,000	$ 109,332,000
Operating Expenses:
Compensation and employee benefits	38,893,000		33,952,000	78,450,000	97,124,000
Systems, technology and telephone	4,809,000		4,110,000	9,123,000	7,939,000
Sales, distribution and marketing	1,202,000		568,000	1,967,000	1,094,000
Occupancy costs	4,025,000		3,352,000	7,502,000	6,532,000
Professional fees	7,602,000		14,863,000	18,972,000	37,747,000
Travel and entertainment	1,326,000		1,306,000	2,737,000	3,252,000
Depreciation and amortization	3,813,000		3,655,000	6,380,000	8,172,000
General, administrative and other	2,738,000		2,538,000	4,757,000	3,971,000
Total operating expenses	64,408,000		64,344,000	129,888,000	165,831,000
Total operating income (loss)	(14,955,000)		(13,059,000)	(29,623,000)	(56,499,000)
Impairment loss on intangible assets	(695,000)	$ (153,600,000)	(29,393,000)	(695,000)	(29,393,000)
Gain (loss) on investments	11,357,000		(5,154,000)	7,696,000	(1,704,000)
Gain (loss) on derivative	0		0	0	0
Gain (loss) on warrant liability	409,000		76,000	69,000	(12,866,000)
Gain (loss) on earnout liability	(1,945,000)		66,083,000	37,509,000	36,877,000
Gain (loss) on TRA	389,000		(1,792,000)	6,322,000	(2,092,000)
Interest expense	(4,851,000)		(3,371,000)	(9,691,000)	(6,632,000)
Interest income	563,000		0	823,000	0
Other income	13,000		(706,000)	(17,000)	(647,000)
Income (loss) before taxes	(9,715,000)		12,684,000	12,393,000	(72,956,000)
Income tax (expense) benefit	756,000		15,446,000	393,000	10,796,000
Net income (loss)	(8,959,000)		28,130,000	12,786,000	(62,160,000)
Strategic Alternatives
Revenue:
Total income	8,553,000		17,321,000	22,534,000	43,836,000
Operating Expenses:
Compensation and employee benefits	9,900,000		12,306,000	22,603,000	39,568,000
Systems, technology and telephone	1,165,000		1,388,000	2,443,000	2,582,000
Sales, distribution and marketing	508,000		213,000	877,000	463,000
Occupancy costs	1,176,000		975,000	2,311,000	2,180,000
Professional fees	3,784,000		6,757,000	8,635,000	19,014,000
Travel and entertainment	518,000		510,000	1,099,000	1,500,000
Depreciation and amortization	406,000		1,518,000	758,000	4,257,000
General, administrative and other	951,000		2,010,000	2,118,000	2,465,000
Total operating expenses	18,408,000		25,677,000	40,844,000	72,029,000
Total operating income (loss)	(9,855,000)		(8,356,000)	(18,310,000)	(28,193,000)
Impairment loss on intangible assets	(695,000)		(29,393,000)	(695,000)
Gain (loss) on investments	(721,000)		(5,585,000)	(4,875,000)	(1,312,000)
Gain (loss) on derivative	0		0	0	0
Gain (loss) on warrant liability	205,000		38,000	35,000	(6,433,000)
Gain (loss) on earnout liability	(593,000)		33,042,000	19,167,000	18,439,000
Gain (loss) on TRA	194,000		(896,000)	3,161,000	(1,046,000)
Interest expense	(2,390,000)		(1,634,000)	(4,768,000)	(3,387,000)
Interest income	241,000		0	364,000	0
Other income	2,000		(367,000)	30,000	(366,000)
Income (loss) before taxes	(13,612,000)		(13,151,000)	(5,891,000)	(51,691,000)
Income tax (expense) benefit	836,000		7,723,000	508,000	5,398,000
Net income (loss)	(12,776,000)		(5,428,000)	(5,383,000)	(46,293,000)
Wealth Management
Revenue:
Total income	40,900,000		33,964,000	77,731,000	65,496,000
Operating Expenses:
Compensation and employee benefits	28,993,000		21,646,000	55,847,000	57,556,000
Systems, technology and telephone	3,644,000		2,722,000	6,680,000	5,357,000
Sales, distribution and marketing	694,000		355,000	1,090,000	631,000
Occupancy costs	2,849,000		2,377,000	5,191,000	4,352,000
Professional fees	3,818,000		8,106,000	10,337,000	18,733,000
Travel and entertainment	808,000		796,000	1,638,000	1,752,000
Depreciation and amortization	3,407,000		2,137,000	5,622,000	3,915,000
General, administrative and other	1,787,000		528,000	2,639,000	1,506,000
Total operating expenses	46,000,000		38,667,000	89,044,000	93,802,000
Total operating income (loss)	(5,100,000)		(4,703,000)	(11,313,000)	(28,306,000)
Impairment loss on intangible assets	0		0	0	0
Gain (loss) on investments	12,078,000		431,000	12,571,000	(392,000)
Gain (loss) on derivative	0		0	0	0
Gain (loss) on warrant liability	204,000		38,000	34,000	(6,433,000)
Gain (loss) on earnout liability	(1,352,000)		33,041,000	18,342,000	18,438,000
Gain (loss) on TRA	195,000		(896,000)	3,161,000	(1,046,000)
Interest expense	(2,461,000)		(1,737,000)	(4,923,000)	(3,245,000)
Interest income	322,000		0	459,000	0
Other income	11,000		(339,000)	(47,000)	(281,000)
Income (loss) before taxes	3,897,000		25,835,000	18,284,000	(21,265,000)
Income tax (expense) benefit	(80,000)		7,723,000	(115,000)	5,398,000
Net income (loss)	3,817,000		33,558,000	18,169,000	(15,867,000)
Management/advisory fees
Revenue:
Total income	47,029,000		46,844,000	93,253,000	93,314,000
Management/advisory fees | Strategic Alternatives
Revenue:
Total income	6,041,000		12,952,000	15,619,000	27,928,000
Management/advisory fees | Wealth Management
Revenue:
Total income	40,988,000		33,892,000	77,634,000	65,386,000
Incentive fees
Revenue:
Total income	53,000		469,000	216,000	1,046,000
Incentive fees | Strategic Alternatives
Revenue:
Total income	52,000		469,000	216,000	1,046,000
Incentive fees | Wealth Management
Revenue:
Total income	1,000		0	0	0
Distributions from investments
Revenue:
Total income	2,240,000		2,203,000	6,410,000	12,233,000
Distributions from investments | Strategic Alternatives
Revenue:
Total income	2,240,000		2,203,000	6,410,000	12,233,000
Distributions from investments | Wealth Management
Revenue:
Total income	0		0	0	0
Other fees/income
Revenue:
Total income	131,000		1,769,000	386,000	2,739,000
Other fees/income | Strategic Alternatives
Revenue:
Total income	220,000		1,697,000	289,000	2,629,000
Other fees/income | Wealth Management
Revenue:
Total income	$ (89,000)		$ 72,000	$ 97,000	$ 110,000