Investments - Summary of Operating and Balance Sheet Data (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Income Statement [Abstract]
Expenses	$ (5,667)	$ (5,620)	$ (11,951)	$ (9,808)
Income tax (expense) benefit	(221)	(226)	(699)	(159)
Net increase in net assets resulting from operations	9,013	17,201	24,132	33,601
Lawn Doctor, Inc.
Income Statement [Abstract]
Revenues	11,882	10,995	21,546	19,789
Expenses	(10,404)	(9,478)	(19,272)	(17,456)
Income (loss) before taxes	1,478	1,517	2,274	2,333
Income tax (expense) benefit	(352)	(388)	(555)	(612)
Consolidated net income (loss)	1,126	1,129	1,719	1,721
Net loss attributable to non-controlling interests	(6)	13	33	88
Net increase in net assets resulting from operations	1,120	1,142	1,752	1,809
Balance Sheet Related Disclosures [Abstract]
Current assets	10,736		10,736		$ 13,926
Non-current assets	90,316		90,316		92,309
Current liabilities	6,730		6,730		7,961
Non-current liabilities	63,461		63,461		63,576
Non-controlling interests	(533)		(533)		(500)
Stockholders’ equity	$ 31,394		$ 31,394		$ 35,198
Ownership percentage	61.00%		61.00%		61.00%
Polyform Products, Co.
Income Statement [Abstract]
Revenues	$ 7,642	4,732	$ 13,465	11,525
Expenses	(6,205)	(4,400)	(11,596)	(9,712)
Income (loss) before taxes	1,437	332	1,869	1,813
Income tax (expense) benefit	(410)	(95)	(534)	(518)
Consolidated net income (loss)	1,027	237	1,335	1,295
Net loss attributable to non-controlling interests	0	0	0	0
Net increase in net assets resulting from operations	1,027	237	1,335	1,295
Balance Sheet Related Disclosures [Abstract]
Current assets	11,484		11,484		$ 9,940
Non-current assets	28,093		28,093		28,948
Current liabilities	2,419		2,419		2,290
Non-current liabilities	21,490		21,490		21,557
Non-controlling interests	0		0		0
Stockholders’ equity	$ 15,668		$ 15,668		$ 15,041
Ownership percentage	87.00%		87.00%		87.00%
Roundtables
Income Statement [Abstract]
Revenues	$ 3,895	3,368	$ 7,438	6,220
Expenses	(3,359)	(3,104)	(7,083)	(6,075)
Income (loss) before taxes	536	264	355	145
Income tax (expense) benefit	(35)	(57)	8	(31)
Consolidated net income (loss)	501	207	363	114
Net loss attributable to non-controlling interests	0	0	0	0
Net increase in net assets resulting from operations	501	207	363	114
Balance Sheet Related Disclosures [Abstract]
Current assets	8,166		8,166		$ 2,043
Non-current assets	60,799		60,799		61,955
Current liabilities	10,326		10,326		4,738
Non-current liabilities	19,777		19,777		19,771
Non-controlling interests	0		0		0
Stockholders’ equity	$ 38,862		$ 38,862		$ 39,489
Ownership percentage	81.00%		81.00%		81.00%
HSH
Income Statement [Abstract]
Revenues	$ 8,260	8,167	$ 17,866	16,130
Expenses	(8,059)	(7,622)	(16,826)	(15,157)
Income (loss) before taxes	201	545	1,040	973
Income tax (expense) benefit	(128)	(120)	(313)	(214)
Consolidated net income (loss)	73	425	727	759
Net loss attributable to non-controlling interests	0	0	0	0
Net increase in net assets resulting from operations	73	425	727	759
Balance Sheet Related Disclosures [Abstract]
Current assets	12,868		12,868		$ 14,260
Non-current assets	37,651		37,651		39,653
Current liabilities	4,698		4,698		7,341
Non-current liabilities	28,643		28,643		28,536
Non-controlling interests	0		0		0
Stockholders’ equity	$ 17,178		$ 17,178		$ 18,036
Ownership percentage	75.00%		75.00%		75.00%
ATA
Income Statement [Abstract]
Revenues	$ 17,214	20,033	$ 31,372	20,033
Expenses	(15,607)	(16,049)	(31,181)	(16,049)
Income (loss) before taxes	1,607	3,984	191	3,984
Income tax (expense) benefit	0	0	0
Consolidated net income (loss)	1,607	3,984	191	3,984
Net loss attributable to non-controlling interests	0	0	0	0
Net increase in net assets resulting from operations	1,607	$ 3,984	191	$ 3,984
Balance Sheet Related Disclosures [Abstract]
Current assets	7,308		7,308		$ 10,029
Non-current assets	90,854		90,854		90,510
Current liabilities	6,798		6,798		9,002
Non-current liabilities	44,262		44,262		43,458
Non-controlling interests	0		0		0
Stockholders’ equity	$ 47,102		$ 47,102		$ 48,079
Ownership percentage	75.00%		75.00%		75.00%
Douglas
Income Statement [Abstract]
Revenues	$ 8,047		$ 13,446
Expenses	(6,883)		(12,707)
Income (loss) before taxes	1,164		739
Income tax (expense) benefit	(285)		(181)
Consolidated net income (loss)	879		558
Net loss attributable to non-controlling interests	0		0
Net increase in net assets resulting from operations	879		558
Balance Sheet Related Disclosures [Abstract]
Current assets	13,412		13,412		$ 13,177
Non-current assets	35,829		35,829		40,311
Current liabilities	4,954		4,954		4,159
Non-current liabilities	15,393		15,393		15,711
Non-controlling interests	0		0		0
Stockholders’ equity	$ 28,894		$ 28,894		$ 33,618
Ownership percentage	90.00%		90.00%		90.00%
Clarion
Income Statement [Abstract]
Revenues	$ 2,814		$ 6,433
Expenses	(3,210)		(6,043)
Income (loss) before taxes	(396)		390
Income tax (expense) benefit	115		(113)
Consolidated net income (loss)	(281)		277
Net loss attributable to non-controlling interests	0		0
Net increase in net assets resulting from operations	(281)		277
Balance Sheet Related Disclosures [Abstract]
Current assets	3,122		3,122		$ 3,084
Non-current assets	70,282		70,282		66,182
Current liabilities	406		406		420
Non-current liabilities	22,500		22,500		22,500
Non-controlling interests	0		0		0
Stockholders’ equity	$ 50,498		$ 50,498		$ 46,346
Ownership percentage	98.00%		98.00%		99.00%
Vektek
Income Statement [Abstract]
Revenues	$ 5,415		$ 5,415
Expenses	(6,552)		(6,552)
Income (loss) before taxes	(1,137)		(1,137)
Income tax (expense) benefit	(8)		(8)
Consolidated net income (loss)	(1,145)		(1,145)
Net loss attributable to non-controlling interests	0		0
Net increase in net assets resulting from operations	(1,145)		(1,145)
Balance Sheet Related Disclosures [Abstract]
Current assets	13,106		13,106
Non-current assets	104,828		104,828
Current liabilities	2,386		2,386
Non-current liabilities	49,191		49,191
Non-controlling interests	0		0
Stockholders’ equity	$ 66,357		$ 66,357
Ownership percentage	84.00%		84.00%