Employee Benefit Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Outstanding stock options and warrants	599,902	611,518
Possible future share issuance authorized under equity incentive plans	2,016,659	2,188,696
Total shares reserved for future issuance	2,616,561	2,800,214
Possible future share issuance authorized under equity incentive plan restricted stock	400,000
Stock-based compensation expense	$ 7,180	$ 7,466	$ 6,692
Total unrecognized stock-based compensation costs	$ 5,200
Weighted average remaining term of vesting periods (in years)	2 years 1 month 6 days
401(k) Savings Plan [Abstract]
401(k) employer match percentage	75.00%
401(k) employer match salary limit percentage	6.00%
401(k) employer contribution	$ 1,500	1,400	1,400
Retirement Plan [Abstract]
Retirement plan qualification years of service (in years)	30 years
Retirement plan qualification age	55 years
Retirement plan qualification minimum years of service (in years)	10 years
Retirement plan immediate vesting percentage	100.00%
Deferred Compensation [Abstract]
Marketable securities of non-qualified deferred compensation plan fair value disclosure	$ 2,345	1,849
Non Qualified Deferred Compensation Obligation Fair Value Disclosure [Roll Forward]
Beginning deferred compensation liability	1,849	2,388	2,451
Mark to market adjustment to deferred compensation (in general and administrative expenses)	496	(182)	492
Distributions from deferred compensation plans	0	(357)	(555)
Ending deferred compensation liability	$ 2,345	$ 1,849	$ 2,388
Employee Stock Purchase Plan [Abstract]
Employee stock purchase plan salary limit percentage	25.00%
Employee stock purchase plan market percentage	85.00%
Number of days at end of quarter used to calculate ESPP discount	5 days
Shares of Common Stock issued under the employee stock purchase plans	38,618	38,951	33,278
Discount percentage on newly issues shares	15.00%
Discount on newly issued shares expensed as additional compensation	$ 300	$ 300	$ 200
Minimum [Member]
Retirement Benefits [Abstract]
Officer cash bonus target	35.00%
Officer cash bonus performance factor	0.00%
Non officer management cash bonus target	6.00%
Maximum [Member]
Retirement Benefits [Abstract]
Officer cash bonus target	135.00%
Officer cash bonus performance factor	200.00%
Non officer management cash bonus target	30.00%
2016 Plan [Member]
Restricted Stock Activity Rollforward [Abstract]
Forfeited (in shares)	(9,521)
2015 Plan [Member]
Restricted Stock Activity Rollforward [Abstract]
Forfeited (in shares)		(13,707)
2014 Plan [Member]
Restricted Stock Activity Rollforward [Abstract]
Awarded and issued (in shares)			34,669
Stock Options [Member]
Retirement Benefits [Abstract]
Grant date fair value of each stock option granted (in dollars per option)			$ 6.72
Assumptions Used in Determining Fair Values of Options/Restricted Stock Granted:
Risk free interest rate			2.00%
Common stock dividend yield			3.40%
Expected volatility rate			19.50%
Average expected option life (in years)			5 years 9 months
Dividends paid for previous year			1 year
Stock Option Activity Rollforward [Abstract]
Balance of options outstanding (in shares)	596,518	640,822	587,115
Options granted (in shares)			168,748
Options exercised (in shares)	(9,026)	(44,304)	(115,041)
Options forfeited (in shares)	(2,590)
Balance of options outstanding (in shares)	584,902	596,518	640,822
Stock Option Activity, Weighted Average Exercise Price Rollforward [Abstract]
Options outstanding, weighted average exercise price (in dollars per share)	$ 45.67	$ 45.29	$ 42.26
Options granted, weighted average exercise price (in dollars per share)			52.49
Options exercised, weighted average exercise price (in dollars per share)	39.53	40.15	40.41
Options forfeited, weighted average exercise price (in dollars per share)	48.79
Options outstanding, weighted average exercise price (in dollars per share)	$ 45.75	$ 45.67	$ 45.29
Weighted average remaining life of outstanding options (in years)	5 years 9 months 18 days
Options exercisable (in shares)	443,783
Weighted average exercise price (in dollars per share)	$ 44.78
Weighted average remaining life (in years)	5 years 7 months 6 days
Intrinsic value	$ 2,100
Amount of exercisable options with prices higher than the market price of Company Common Stock	84,374
Cash received or receivable from options exercised	$ 400	$ 1,900	$ 5,200
Total instrinsic value of options exercised	100	400	1,300
Total intrinsic value of options outstanding	$ 2,400	$ 100	$ 3,900
2014 to 2017 Stock Options [Member]
Retirement Benefits [Abstract]
Vesting term of stock options issued/Period for absolute total return of restricted stock issued (in years)	4 years
Option expiration period (in years)	10 years
2013 Stock Options [Member]
Retirement Benefits [Abstract]
Vesting term of stock options issued/Period for absolute total return of restricted stock issued (in years)	4 years
Option expiration period (in years)	7 years
Time-Based Restricted Stock [Member]
Retirement Benefits [Abstract]
Vesting term of stock options issued/Period for absolute total return of restricted stock issued (in years)	4 years
Restricted Stock Activity Rollforward [Abstract]
Balance of restricted stock outstanding (in shares)	191,239	172,246	188,981
Awarded and issued (in shares)	103,590	94,984	61,404
Vested (in shares)	(73,036)	(73,307)	(78,139)
Forfeited (in shares)	(3,642)	(2,684)
Balance of restricted stock outstanding (in shares)	218,151	191,239	172,246
Restricted Stock Activity, Weighted Average Grant Date Fair Value Rollforward [Abstract]
Restricted stock outstanding, weighted average grant date fair value (in dollars per share)	$ 45.62	$ 46.46	$ 42.06
Awarded and issued, weighted average grant date fair value (in dollars per share)	45.98	43.01	52.49
Vested, weighted average grant date fair value (in dollars per share)	45.79	44.19	40.55
Forfeited, weighted average grant date fair value (in dollars per share)	46.07	45.89
Restricted stock outstanding, weighted average grant date fair value (in dollars per share)	45.73	45.62	46.46
Grant date fair value of restricted stock (in dollars per share)	$ 45.98	$ 43.01	$ 52.49
Fair value at grant date of restricted stock issued	$ 4,800	$ 4,100	$ 3,200
Vesting date fair value of restricted stock	$ 3,300	$ 3,200	$ 4,100
Total Return-Based Restricted Stock [Member]
Retirement Benefits [Abstract]
Vesting term of stock options issued/Period for absolute total return of restricted stock issued (in years)	3 years
Assumptions Used in Determining Fair Values of Options/Restricted Stock Granted:
Risk free interest rate	2.40%	2.30%	1.60%
Common stock dividend yield	4.40%	3.90%	3.50%
Expected volatility rate	27.30%	41.10%	42.80%
Dividends paid for previous year	1 year
Restricted Stock Activity Rollforward [Abstract]
Balance of restricted stock outstanding (in shares)	180,094	160,724	183,724
Awarded and issued (in shares)	87,344	77,456	84,013
Vested (in shares)	(45,901)	(41,160)	(107,013)
Forfeited (in shares)	(12,689)	(16,926)
Balance of restricted stock outstanding (in shares)	208,848	180,094	160,724
Restricted Stock Activity, Weighted Average Grant Date Fair Value Rollforward [Abstract]
Restricted stock outstanding, weighted average grant date fair value (in dollars per share)	$ 43.34	$ 44.72	$ 39.82
Awarded and issued, weighted average grant date fair value (in dollars per share)	39.42	40.81	44.76
Vested, weighted average grant date fair value (in dollars per share)	43.68	45.61	37.88
Forfeited, weighted average grant date fair value (in dollars per share)	43.58	45.24
Restricted stock outstanding, weighted average grant date fair value (in dollars per share)	$ 42.22	43.34	44.72
Company total return, total return-based restricted stock	100.00%
Vesting percentage, total return-based restricted stock	75.00%
Grant date fair value of restricted stock (in dollars per share)	$ 39.42	$ 40.81	$ 44.76
Fair value at grant date of restricted stock issued	$ 3,400	$ 3,200	$ 2,400
Vesting date fair value of restricted stock	$ 2,100	$ 1,800	$ 5,600
Period preceding date of grant	3 months
Total Return-Based Restricted Stock [Member] | Minimum [Member]
Restricted Stock Activity, Weighted Average Grant Date Fair Value Rollforward [Abstract]
Percentage of return-based restricted stock issued to officers that will vest	0.00%
Total Return-Based Restricted Stock [Member] | Maximum [Member]
Restricted Stock Activity, Weighted Average Grant Date Fair Value Rollforward [Abstract]
Percentage of return-based restricted stock issued to officers that will vest	150.00%
Total Return-Based Restricted Stock Current Year Issuance [Member]
Restricted Stock Activity, Weighted Average Grant Date Fair Value Rollforward [Abstract]
Awarded and issued, weighted average grant date fair value (in dollars per share)	$ 39.42	$ 40.81	$ 49.59
Grant date fair value of restricted stock (in dollars per share)	$ 39.42	$ 40.81	$ 49.59