Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Deferred Compensation Arrangements [Abstract]

Schedule of Stock Option Valuation Assumptions [Table Text Block]

The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model with the following weighted average assumptions:



	2019	2018	2017
Dividend yield	5.5%	6.5%	5.3%
Expected volatility	18.2%	19.4%	19.8%
Expected lives	2.7 years	2.9 years	2.9 years
Risk-free interest rate	2.39%	2.39%	1.49%

Schedule of Stock Option Activity [Table Text Block]

The following tables summarize our outstanding stock options, after giving effect to modifications of 83,334 options in November 2019 as, in substance, the forfeiture of old and issuance of new options concurrent with an employee’s retirement:



				Weighted Average
	Number		Weighted Average	Remaining	Aggregate
	of Shares		Exercise Price	Contractual Life (Years)	Intrinsic Value
Outstanding December 31, 2016	541,679		$65.84
Options granted under 2012 Plan	495,000		$74.90
Options granted under 2005 Plan	—		$0.00
Options exercised under 2005 Plan	(15,000	)	$47.52
Options exercised under 2012 Plan	(155,829	)	$65.73
Options canceled under 2012 Plan	(6,668	)	$60.52
Outstanding December 31, 2017	859,182		$70.11
Options granted under 2012 Plan	560,000		$64.33
Options granted under 2005 Plan	—		$0.00
Options exercised under 2005 Plan	(6,668	)	$72.11
Options exercised under 2012 Plan	(462,167	)	$65.03
Options canceled under 2012 Plan	(30,001	)	$66.73
Outstanding December 31, 2018	920,346		$69.24
Options granted under 2012 Plan	685,334		$79.08
Options exercised under 2012 Plan	(501,664	)	$71.52
Options forfeited under 2012 Plan	(100,002	)	$73.89
Options forfeited under 2005 Plan	—		$0.00
Options outstanding, December 31, 2019	1,004,014		$74.35	3.24	$	7,157,000

Exercisable at December 31, 2019	530,163		$73.93	2.91	$	4,001,000



				Remaining
Grant	Number	Exercise		Contractual
Date	of Shares	Price		Life in Years
2/20/2015	20,000	$	72.11	0.14
2/22/2016	20,000	$	60.52	1.15
2/22/2017	121,669	$	74.78	2.15
2/20/2018	246,177	$	64.33	3.14
2/21/2019	512,834	$	79.96	4.15
11/7/2019	83,334	$	72.67	0.85
Options outstanding, December 31, 2019	1,004,014

Schedule of Nonvested Share Activity [Table Text Block]

The following table summarizes our outstanding non-vested stock options:



	Number of Shares		Weighted Average Grant Date Fair Value
Non-vested December 31, 2018	443,354		$4.87
Options granted under 2012 Plan	685,334		$6.11
Options vested under 2012 Plan	(554,835	)	$5.62
Non-vested options forfeited under 2012 Plan	(100,002	)	$5.56
Non-vested December 31, 2019	473,851		$5.64