Note 4 - Share-based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

Notes Tables

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	2017						2016
	Class A			Class B			Class A			Class B
Expected dividend yield at date of grant	2.46	to	2.87%	7.99	to	8.10%	2.96	to	3.02%	6.67	to	8.12%
Expected stock price volatility	32.20	to	32.62%	26.47	to	27.18%	31.33	to	34.61%	27.64	to	31.77%
Risk-free interest rate	2.08	to	2.33%	2.08	to	2.33%	1.36	to	2.12%	1.36	to	2.12%
Expected life of options (in years)	6	to	8	6	to	8	6	to	8	6	to	8

Share-based Compensation, Activity [Table Text Block]

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Terms (Years)		Aggregate Intrinsic Value (In thousands)
Class A
Outstanding at December 31, 2016		1,705,483		$	12.31
Granted		299,917		$	22.13
Exercised		(161,784	)	$	11.01			$	1,808
Forfeited		(60,982	)	$	21.35
Outstanding at September 30, 2017		1,782,634		$	13.77		5.54	$	42,651
Exercisable at September 30, 2017		1,310,361		$	12.04		4.46	$	33,621
Class B
Outstanding at December 31, 2016		250,493		$	29.70
Granted		49,986		$	42.90
Exercised		(12,000	)	$	28.41			$	142
Forfeited		(10,163	)	$	41.53
Outstanding at September 30, 2017		278,316		$	31.69		5.74	$	6,044
Exercisable at September 30, 2017		200,550		$	29.06		4.66	$	4,884

Schedule of Nonvested Share Activity [Table Text Block]

	Class A Shares Outstanding			Class A Weighted Average Grant Date Fair Value Per Share		Class B Shares Outstanding			Class B Weighted Average Grant Date Fair Value Per Share
Outstanding at December 31, 2016		174,487		$	13.93		29,081		$	37.21
Granted		--			--		--			--
Vested		--			--		--			--
Forfeited		(19,314	)	$	14.26		(3,219	)	$	34.69
Outstanding at September 30, 2017		155,173		$	13.89		25,862		$	37.53