Clearfield, Inc. Quarterly report pursuant to Section 13 or 15(d)

Note 4 - Fair Value Measurements - Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Fair value	$ 29,187
Fair Value, Inputs, Level 1 [Member]
Fair value	0
Fair Value, Inputs, Level 2 [Member]
Fair value	29,187
Fair Value, Inputs, Level 3 [Member]
Fair value	0	$ 0
US Treasury Securities [Member]
Fair value	15,463
US Treasury Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value	0
US Treasury Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value	15,463
US Treasury Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value	0
Certificates of Deposit [Member]
Fair value	13,724
Certificates of Deposit [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value	0
Certificates of Deposit [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value	13,724
Certificates of Deposit [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value	$ 0