Note 1 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

Schedule of Deferred Compensation Plan [Table Text Block]

	December 31,
	2020		2019
Deferred compensation plan asset components:
Cash surrender value of corporate-owned life insurance policies	$	19,222	$	16,883
Fair value of mutual funds and money market funds		26,924		21,975
Total	$	46,146	$	38,858
Deferred compensation plan assets reported in:
Other long-term assets	$	46,146	$	38,858
Deferred compensation plan liabilities reported in:
Accrued compensation and related benefits (short-term)	$	155	$	425
Other long-term liabilities		48,280		39,665
Total	$	48,435	$	40,090