Note 6 - Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Notes Tables

Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]

	Time-Based RSUs					Performance-Based RSUs
				Weighted-Average					Weighted-Average
				Grant Date					Grant Date
	Shares			Fair Value		Shares			Fair Value
Balance at December 31, 2020		292,670		$	33.37		302,802		$	32.55
Granted		13,509			39.77		—			—
Vested		(91,654	)		41.88		(8,537	)		43.37
Forfeited		(16,296	)		30.62		(5,008	)		40.60
Balance at March 31, 2021		198,229		$	30.10		289,257		$	32.09