Note 9 - Stock Based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

Notes Tables

Share-based Compensation, Stock Options, Activity [Table Text Block]

Options	Number of Shares			Weighted Average Exercise Price
Outstanding at December 31, 2016		1,519,338		$	25.22
Granted		39,037			54.15
Exercised		(61,249	)		11.83
Outstanding at March 31, 2017		1,497,126			26.52
Granted		19,598			58.98
Exercised		(162,431	)		13.84
Outstanding at June 30, 2017		1,354,293			28.51
Exercised		(55,950	)		8.48
Outstanding at September 30, 2017		1,298,343			29.37
Exercisable at September 30, 2017		449,959		$	21.09

Schedule of Nonvested Share Activity [Table Text Block]

	Unvested Stock Options					Unvested Restricted Stock					Unvested Performance Shares
	Number of Shares			Weighted- Average Grant-Date Fair Value		Number of Shares			Weighted- Average Grant-Date Fair Value		Number of Shares			Weighted- Average Grant-Date Fair Value
Unvested at December 31, 2016		817,540		$	12.50		260		$	41.05		316,750		$	30.08
Granted		39,037			21.02		-			-		-			-
Vested during period		(14,975	)		8.16		-			-		-			-
Unvested at March 31, 2017		841,602			12.97		260			41.05		316,750			30.08
Granted		19,598			18.37		9,496			58.98		5,750			41.36
Vested during period		(12,816	)		8.50		(260	)		41.05		-			-
Unvested at June 30, 2017		848,384			13.17		9,496			58.98		322,500			30.28
Vested during period		-			-		-			-		(150,000	)		17.81
Unvested at September 30, 2017		848,384		$	13.17		9,496		$	58.98		172,500		$	41.12