Note 11 - Stockholders' Equity and Stock Incentive Plans - Career Share Activity (Details) - Career Shares [Member] - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Outstanding, units (in shares)	1,021,285	1,013,459	1,041,639
Granted, units (in shares)	67,719	40,492	66,000
Granted, weighted average grant date fair value, units (in dollars per share)	$ 21.27	$ 34.48	$ 20.41
Canceled, units (in shares)	0	(5,335)	(11,236)
Awarded, units (in shares)	(26,693)	(27,331)	(82,944)
Outstanding, units (in shares)	1,062,311	1,021,285	1,013,459