Note 12 - Fair Value Measurements - Assets Measured At Fair Value On a Recurring and Nonrecurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands		Dec. 31, 2021	Jun. 30, 2021
Assets measured on a recurring basis		$ 137,754	$ 151,577
US Government Agencies Debt Securities [Member]
Assets measured on a recurring basis		3,182	3,214
Corporate Debt Securities [Member]
Assets measured on a recurring basis		96,776	110,040
Debt Security, Corporate, Non-US [Member]
Assets measured on a recurring basis	[1]	37,085	37,598
US States and Political Subdivisions Debt Securities [Member]
Assets measured on a recurring basis		711	725
Fair Value, Inputs, Level 1 [Member]
Assets measured on a recurring basis		0	0
Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities [Member]
Assets measured on a recurring basis		0	0
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Assets measured on a recurring basis		0	0
Fair Value, Inputs, Level 1 [Member] | Debt Security, Corporate, Non-US [Member]
Assets measured on a recurring basis	[1]	0	0
Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets measured on a recurring basis		0	0
Fair Value, Inputs, Level 2 [Member]
Assets measured on a recurring basis		137,754	151,577
Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member]
Assets measured on a recurring basis		3,182	3,214
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Assets measured on a recurring basis		96,776	110,040
Fair Value, Inputs, Level 2 [Member] | Debt Security, Corporate, Non-US [Member]
Assets measured on a recurring basis	[1]	37,085	37,598
Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets measured on a recurring basis		711	725
Fair Value, Inputs, Level 3 [Member]
Assets measured on a recurring basis		0	0
Fair Value, Inputs, Level 3 [Member] | US Government Agencies Debt Securities [Member]
Assets measured on a recurring basis		0	0
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Assets measured on a recurring basis		0	0
Fair Value, Inputs, Level 3 [Member] | Debt Security, Corporate, Non-US [Member]
Assets measured on a recurring basis	[1]	0	0
Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets measured on a recurring basis		$ 0	$ 0

[1] U.S. dollar-denominated investment-grade corporate bonds of large foreign corporate issuers.