Stock Option And Stock Award Plans (Summary Of Additional Information On Stock Options Outstanding And Exercisable) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Shares	2,827,438
Options Outstanding, Weighted Average, Remaining Contractual Life (Years)	4 years 10 months 24 days
Options Outstanding, Weighted Average, Exercise Price	$ 13.55
Options Outstanding, Aggregate Intrinsic Value	$ 9,548,207
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	1,287,792	360,218
Options Exercisable, Weighted Average Exercise Price	$ 14.68
Options Exercisable, Aggregate Intrinsic Value	$ 3,233,338
Share-based Compensation Arrangement by Share-based Payment Award, Options, modification	701,535
Dividend yield	2.50%	2.40%	2.30%
Weighted average volatility percentage	43.80%	38.30%	38.30%
Weighted average risk-free interest rate	0.80%	2.40%	2.80%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 10.75	$ 13.78	$ 14.43
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	2,827,438	1,628,903	890,116	608,520
Estimated weighted average fair value of options per share at date of grant	$ 4.44	$ 5.43	$ 5.87
Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period, Fair Value	$ 2,833	$ 4,117	$ 2,648
Officers
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Holding period (years):	5 years	5 years	5 years
Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share Based Compensation Arrangements By Share Based Payment Award, Options, Modification, Exercise Price	10.75
Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share Based Compensation Arrangements By Share Based Payment Award, Options, Modification, Exercise Price	14.62
- To 15.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	$ 0
Range of Exercise Prices, Maximum	$ 13.99
Options Outstanding, Shares	1,598,700
Options Outstanding, Weighted Average, Remaining Contractual Life (Years)	5 years 4 months 24 days
Options Outstanding, Weighted Average, Exercise Price	$ 12.11
Options Outstanding, Aggregate Intrinsic Value	$ 7,338,799
Options Exercisable, Shares	425,219
Options Exercisable, Weighted Average Exercise Price	$ 12.50
Options Exercisable, Aggregate Intrinsic Value	$ 1,785,553
15.01 To 17.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	$ 13.99
Range of Exercise Prices, Maximum	$ 18.65
Options Outstanding, Shares	1,059,138
Options Outstanding, Weighted Average, Remaining Contractual Life (Years)	4 years 4 months 24 days
Options Outstanding, Weighted Average, Exercise Price	$ 14.64
Options Outstanding, Aggregate Intrinsic Value	$ 2,209,408
Options Exercisable, Shares	692,973
Options Exercisable, Weighted Average Exercise Price	$ 14.66
Options Exercisable, Aggregate Intrinsic Value	$ 1,447,785
17.51 To 20.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	$ 18.65
Range of Exercise Prices, Maximum	$ 23.32
Options Outstanding, Shares	169,600
Options Outstanding, Weighted Average, Remaining Contractual Life (Years)	2 years 1 month 6 days
Options Outstanding, Weighted Average, Exercise Price	$ 20.27
Options Outstanding, Aggregate Intrinsic Value	$ 0
Options Exercisable, Shares	169,600
Options Exercisable, Weighted Average Exercise Price	$ 20.27
Options Exercisable, Aggregate Intrinsic Value	$ 0