Note 9 - Share-based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Notes Tables

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

	2016						2015						2014
	Class A			Class B			Class A			Class B			Class A			Class B
Expected dividend yield at date of grant	2.96	to	3.02%	6.67	to	8.12%	2.00	to	2.57%	5.29	to	5.72%	1.47	to	1.97%	4.03	to	4.87%
Expected stock price volatility	31.33	to	34.61%	27.64	to	31.77%	30.86	to	34.87%	29.72	to	33.94%	27.52	to	32.03%	30.13	to	32.65%
Risk-free interest rate	1.36	to	2.12%	1.36	to	2.12%	1.41	to	1.78%	1.41	to	1.78%	1.63	to	2.37%	1.63	to	2.37%
Expected life of options (in years)	6	to	8	6	to	8	5	to	7	5	to	7	5	to	7	5	to	7

Schedule of 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, 201 5		1,485,738		$	11.65
Granted		315,620		$	14.64
Exercised		(52,383	)	$	6.59			$	459
Forfeited		(43,492	)	$	13.25
Outstanding at December 31, 2016		1,705,483		$	12.31		5.87	$	11,404
Exercisable at December 31, 2016		1,250,793		$	11.64		4.96	$	9,203
Class B
Outstanding at December 31, 201 5		240,673		$	26.31
Granted		52,603		$	36.16
Exercised		(35,534	)	$	16.88			$	632
Forfeited		(7,249	)	$	26.90
Outstanding at December 31, 2016		250,493		$	29.70		6.32	$	3,066
Exercisable at December 31, 2016		175,659		$	27.82		5.43	$	2,500

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, 201 5		183,814		$	12.78		30,635		$	36.93
Granted		20,578		$	15.23		3,430		$	34.00
Vested		(20,892	)	$	5.38		(3,482	)	$	32.31
Forfeited		(9,013	)	$	13.17		(1,502	)	$	35.48
Outstanding at December 31, 2016		174,487		$	13.93		29,081		$	37.21