Consolidated Investment Products - Schedule of Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Condensed Income Statements, Captions [Line Items]
Revenue	$ 19,761		$ 11,442		$ 39,560	$ 23,572
Operating expenses:
Compensation, related employee benefits, and cost of goods sold	8,384		6,338		17,951	12,684
Sales, distribution and marketing	4,441		2,719		8,897	4,909
Depreciation and amortization	342		459		841	919
General and administrative expenses	2,971		2,090		5,850	4,734
Impairment of goodwill	900				900
Expenses of consolidated investment products	217		501		1,312	1,065
Total operating expenses	17,255		12,107		35,751	24,311
Operating income (loss)	2,506		(665)		3,809	(739)
Other income (expense):
Equity in earnings of proprietary funds, net	(4,561)		1,711		(1,510)	2,231
Interest and dividends	454		181		945	370
Other income (expense)	(190)		(46)		(241)	(173)
Unrealized gain (loss) on digital assets, net	3,428		(1,296)		1,649	2,887
Realized gain on investments, net	(2)		127		2,197	319
Unrealized gain (loss) on investments net	(15,422)		8,942		(1,689)	13,622
Total other income, net	(29,939)		42,348		60,877	327,711
Income before provision for income taxes	(27,433)		41,683		64,686	326,972
Income tax (expense) benefit	4,083		(234)		(6,201)	(1,478)
Net income (loss)	(23,350)		41,449		58,485	325,494
Less: net income attributable to redeemable noncontrolling interests	12,861		(27,411)		(46,133)	(270,615)
Net (loss) income attributable to Horizon Kinetics Holding Corporation	(10,489)	$ 22,841	14,038	$ 40,841	12,352	54,879
Management and Advisory Fees
Condensed Income Statements, Captions [Line Items]
Revenue	18,798		11,323		37,703	23,315
Other Income and Fees
Condensed Income Statements, Captions [Line Items]
Revenue	963		119		1,857	257
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenue					(3,976)	(3,486)
Operating expenses:
General and administrative expenses					(44)	43
Expenses of consolidated investment products					44	43
Total operating expenses						86
Operating income (loss)					(3,976)	(3,572)
Other income (expense):
Equity in earnings of proprietary funds, net					(8,149)	(33,246)
Management fees of consolidated investment products					(3,758)	(2,998)
Total other income, net					(11,907)	(36,244)
Income before provision for income taxes					(15,883)	(39,816)
Net income (loss)					(15,883)	(39,816)
Less: net income attributable to redeemable noncontrolling interests					1,381	1,772
Net (loss) income attributable to Horizon Kinetics Holding Corporation					(14,502)	(38,044)
Eliminations \| Management and Advisory Fees
Condensed Income Statements, Captions [Line Items]
Revenue					(3,976)	(3,486)
Consolidated Company Entities \| Operating Segment
Condensed Income Statements, Captions [Line Items]
Revenue					43,536	27,058
Operating expenses:
Compensation, related employee benefits, and cost of goods sold					17,951	12,684
Sales, distribution and marketing					8,897	4,909
Depreciation and amortization					841	919
General and administrative expenses					5,894	4,691
Impairment of goodwill					900
Total operating expenses					34,483	23,203
Operating income (loss)					9,053	3,855
Other income (expense):
Equity in earnings of proprietary funds, net					6,639	35,477
Interest and dividends					945	370
Other income (expense)					(241)	(173)
Unrealized gain (loss) on digital assets, net					1,649	2,887
Realized gain on investments, net					2,197	319
Unrealized gain (loss) on investments net					(1,689)	13,622
Total other income, net					9,500	52,502
Income before provision for income taxes					18,553	56,357
Income tax (expense) benefit					(6,201)	(1,478)
Net income (loss)					12,352	54,879
Net (loss) income attributable to Horizon Kinetics Holding Corporation					12,352	54,879
Consolidated Company Entities \| Operating Segment \| Management and Advisory Fees
Condensed Income Statements, Captions [Line Items]
Revenue					41,679	26,801
Consolidated Company Entities \| Operating Segment \| Other Income and Fees
Condensed Income Statements, Captions [Line Items]
Revenue					1,857	257
Consolidated Investment Products
Other income (expense):
Interest and dividends	1,887		4,780		4,792	8,606
Other income (expense)	$ (15,533)		$ 27,949		54,734	299,849
Consolidated Investment Products \| Operating Segment
Operating expenses:
Expenses of consolidated investment products					1,268	1,022
Total operating expenses					1,268	1,022
Operating income (loss)					(1,268)	(1,022)
Other income (expense):
Interest and dividends					4,792	8,606
Other income (expense)					54,734	299,849
Management fees of consolidated investment products					3,758	2,998
Total other income, net					63,284	311,453
Income before provision for income taxes					62,016	310,431
Net income (loss)					62,016	310,431
Less: net income attributable to redeemable noncontrolling interests					(47,514)	(272,387)
Net (loss) income attributable to Horizon Kinetics Holding Corporation					$ 14,502	$ 38,044

Horizon Kinetics Holding Corp 10-Q