Note 11 - Share Based Compensation and Employee Benefit Plans - Stock Option (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Balance (in shares) | shares	2,724,308
Balance, weighted average exercise price (in dollars per share) | $ / shares	$ 24.78
Granted (in shares) | shares	459,663
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 42.99
Exercised (in shares) | shares	(126,027)
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 21.77
Forfeited (in shares) | shares	(73,664)
Forfeited, weighted average exercise price (in dollars per share) | $ / shares	$ 28.21
Balance (in shares) | shares	2,984,280
Balance, weighted average exercise price (in dollars per share) | $ / shares	$ 27.63
Balance, weighted average remaining contractual life (Year)	6 years 14 days
Aggregate intrinsic value | $	$ 24,290,404
Expected to vest (in shares) | shares	1,750,298
Expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 30.62
Expected to vest, weighted average remaining contractual life (Year)	7 years 229 days
Expected to vest, aggregate intrinsic value | $	$ 10,524,034
Vested and exercisable (in shares) | shares	1,187,924
Vested and exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 23.15
Vested and exercisable, weighted average remaining contractual life (Year)	3 years 233 days
Vested and exercisable, aggregate intrinsic value | $	$ 13,457,583