Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Mar. 31, 2023	Mar. 31, 2022
Common Stock [Member] | Common Class A [Member]
Statement [Line Items]
Balance (in shares)	13,866,999	13,866,999	13,866,999	13,866,913	13,866,913	13,866,913	13,866,999	13,866,913
Balance	$ 347	$ 347	$ 347	$ 347	$ 347	$ 347	$ 347	$ 347
Repurchases of shares of Common Stock (class A) (in shares)	0	0	0	0	0	0
Repurchases of shares of Common Stock (class A)	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Issuance of stock under ESPP of shares of Common Stock (class A) (in shares)	0	0	0	0	0	0
Issuance of stock under ESPP of shares of Common Stock (class A)	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Share-based compensation, adjustment for forfeitures, net of tax			0
Dividends declared	0	0	0	0	0	0
Net other comprehensive loss	0	0	0	0	0	0
Net income	$ 0	$ 0	$ 0	$ 0	0	0
Share-based compensation, net of tax					$ 0	$ 0
Balance (in shares)	13,866,999	13,866,999	13,866,999	13,866,913	13,866,913	13,866,913	13,866,999	13,866,913
Balance	$ 347	$ 347	$ 347	$ 347	$ 347	$ 347	$ 347	$ 347
Common Stock [Member] | Common Class C [Member]
Statement [Line Items]
Balance (in shares)	2,068,549	2,068,549	2,068,549	2,068,635	2,068,635	2,068,635	2,068,549	2,068,635
Balance	$ 52	$ 52	$ 52	$ 52	$ 52	$ 52	$ 52	$ 52
Repurchases of shares of Common Stock (class A) (in shares)	0	0	0	0	0	0
Repurchases of shares of Common Stock (class A)	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Issuance of stock under ESPP of shares of Common Stock (class A) (in shares)	0	0	0	0	0	0
Issuance of stock under ESPP of shares of Common Stock (class A)	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Share-based compensation, adjustment for forfeitures, net of tax			0
Dividends declared	0	0	0	0	0	0
Net other comprehensive loss	0	0	0	0	0	0
Net income	$ 0	$ 0	$ 0	$ 0	0	0
Share-based compensation, net of tax					$ 0	$ 0
Balance (in shares)	2,068,549	2,068,549	2,068,549	2,068,635	2,068,635	2,068,635	2,068,549	2,068,635
Balance	$ 52	$ 52	$ 52	$ 52	$ 52	$ 52	$ 52	$ 52
Additional Paid-in Capital [Member]
Statement [Line Items]
Balance	16,441	16,440	16,438	16,425	16,073	15,677	16,438	15,677
Repurchases of shares of Common Stock (class A)	0	0	0	0	0	0
Issuance of stock under ESPP of shares of Common Stock (class A)	1	1	3	7	7	8
Share-based compensation, adjustment for forfeitures, net of tax			(1)
Dividends declared	0	0	0	0	0	0
Net other comprehensive loss	0	0	0	0	0	0
Net income	0	0	0	0	0	0
Share-based compensation, net of tax					345	388
Balance	$ 16,442	$ 16,441	$ 16,440	$ 16,432	$ 16,425	$ 16,073	$ 16,442	$ 16,432
Treasury Stock, Common [Member] | Common Class A [Member]
Statement [Line Items]
Repurchases of shares of Common Stock (class A) (in shares)	193,040			19,487			320,412	43,591
Treasury Stock, Common [Member]
Statement [Line Items]
Balance (in shares)	1,096,540	1,014,031	978,049	918,287	910,372	898,953	978,049	898,953
Balance	$ (2,958)	$ (2,722)	$ (2,599)	$ (2,297)	$ (2,248)	$ (2,172)	$ (2,599)	$ (2,172)
Repurchases of shares of Common Stock (class A) (in shares)	193,040	87,407	39,965	19,487	10,457	13,647
Repurchases of shares of Common Stock (class A)	$ (556)	$ (249)	$ (133)	$ (97)	$ (54)	$ (82)
Issuance of stock under ESPP of shares of Common Stock (class A) (in shares)	(5,486)	(4,898)	(3,983)	(2,470)	(2,542)	(2,228)
Issuance of stock under ESPP of shares of Common Stock (class A)	$ 15	$ 13	$ 10	$ 6	$ 5	$ 6
Share-based compensation, adjustment for forfeitures, net of tax			0
Dividends declared	0	0	0	0	0	0
Net other comprehensive loss	0	0	0	0	0	0
Net income	$ 0	$ 0	$ 0	$ 0	0	0
Share-based compensation, net of tax					$ 0	$ 0
Balance (in shares)	1,284,094	1,096,540	1,014,031	935,304	918,287	910,372	1,284,094	935,304
Balance	$ (3,499)	$ (2,958)	$ (2,722)	$ (2,388)	$ (2,297)	$ (2,248)	$ (3,499)	$ (2,388)
AOCI Attributable to Parent [Member]
Statement [Line Items]
Balance	1,890	3,138	3,624	5,365	5,952	6,587	3,624	6,587
Repurchases of shares of Common Stock (class A)	0	0	0	0	0	0
Issuance of stock under ESPP of shares of Common Stock (class A)	0	0	0	0	0	0
Share-based compensation, adjustment for forfeitures, net of tax			0
Dividends declared	0	0	0	0	0	0
Net other comprehensive loss	(231)	(1,248)	(486)	(568)	(587)	(635)	(1,965)	(1,790)
Net income	0	0	0	0	0	0
Share-based compensation, net of tax					0	0
Balance	1,659	1,890	3,138	4,797	5,365	5,952	1,659	4,797
Retained Earnings [Member]
Statement [Line Items]
Balance	36,608	36,074	36,302	39,137	35,885	33,833	36,302	33,833
Repurchases of shares of Common Stock (class A)	0	0	0	0	0	0
Issuance of stock under ESPP of shares of Common Stock (class A)	0	0	0	0	0	0
Share-based compensation, adjustment for forfeitures, net of tax			0
Dividends declared	(329)	(335)	(335)	(337)	(338)	(338)
Net other comprehensive loss	0	0	0	0	0	0
Net income	1,640	869	107	(846)	3,590	2,390
Share-based compensation, net of tax					0	0
Balance	37,919	36,608	36,074	37,954	39,137	35,885	37,919	37,954
Balance	52,380	53,329	54,164	59,029	56,061	54,324	54,164	54,324
Repurchases of shares of Common Stock (class A)	(556)	(249)	(133)	(97)	(54)	(82)
Issuance of stock under ESPP of shares of Common Stock (class A)	16	14	13	13	12	14
Share-based compensation, adjustment for forfeitures, net of tax			(1)
Dividends declared	(329)	(335)	(335)	(337)	(338)	(338)
Net other comprehensive loss	(231)	(1,248)	(486)	(568)	(587)	(635)	(1,965)	(1,790)
Net income	1,640	869	107	(846)	3,590	2,390	2,616	5,134
Share-based compensation, net of tax					345	388
Balance	$ 52,920	$ 52,380	$ 53,329	$ 57,194	$ 59,029	$ 56,061	$ 52,920	$ 57,194