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Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Restricted Stock, Shares
Expired (in shares)	0
Restricted Stock, Weighted- Average Grant Date Fair Value
Expired (in dollars per share)	$ 0.00
Stock Options, Shares
Outstanding at beginning of period (in shares)	81,000
Granted (in shares)	0
Exercised (in shares)	(78,000)
Forfeited (in shares)	0
Expired (in shares)	0
Outstanding at end of period (in shares)	3,000
Stock Options, Weighted- Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 11.94
Granted (in dollars per share)	0.00
Exercised (in dollars per share)	11.92
Forfeited (in dollars per share)	0.00
Expired (in dollars per share)	0.00
Outstanding at end of period (in dollars per share)	12.38
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average grant date fair value of options granted (in dollars per share)	$ 0.00	$ 0.00
Total fair value of options that vested	$ 0	$ 0
Total intrinsic value of options exercised	2,582	$ 2,711
Chairman, President, and Chief Executive Officer | Common Stock | Achieves a specific performance target by the end of 2019 and she remains an employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares received if achieves specified improvement in total shareholders return (in shares)				53,859
Chairman, President, and Chief Executive Officer | Common Stock | Achieves a specific performance target by the end of 2017 and she remains an employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares received if achieves specified improvement in total shareholders return (in shares)				17,953
Restricted Shares and Performance Based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense related to stock awards	$ 6,500
Period of time stock expense is expected to be recognized	1 year 8 months 26 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected quarterly dividends per share (in dollars per share)	$ 0.2900	$ 0.2650
Risk-free interest rate	2.50%	2.39%
Restricted Stock
Restricted Stock, Shares
Outstanding at beginning of period (in shares)	166,651
Granted (in shares)	114,611
Exercised (in shares)	(118,427)
Forfeited (in shares)	0
Expired (in shares)	0
Outstanding at end of period (in shares)	162,835
Restricted Stock, Weighted- Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share)	$ 32.93
Granted (in dollars per share)	36.48	$ 29.03
Exercised (in dollars per share)	30.97
Forfeited (in dollars per share)	0.00
Expired (in dollars per share)	0.00
Outstanding at end of period (in dollars per share)	$ 36.86
Stock Options, Shares
Expired (in shares)	0
Stock Options, Weighted- Average Exercise Price
Expired (in dollars per share)	$ 0.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average grant date fair value (in dollars per share)	$ 36.48	$ 29.03
Total fair value of restricted shares that vested	$ 5,314	$ 7,162
Performance Shares | Executive
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares awarded in year one (in shares)	130,302		47,279
Weighted percentage assigned to achieving market targets			40.00%
Weighted percentage assigned to achieving performance targets			60.00%
Maximum number of shares awarded in year two (in shares)	146,941
Maximum number of shares in year three (in shares)	135,678
Performance period	3 years
Market-Based Shares
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate	2.51%	2.36%
Dividend yield	2.59%	2.96%
Expected volatility	19.55%	19.12%
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of stock options outstanding	$ 100
Weighted-average remaining contract life	1 year
Number of outstanding stock options with an exercise price greater than the closing price (in shares)	0
Performance Equity Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Vesting rate	100.00%

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