Stock-Based Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Additional Disclosures [Abstract]
Compensation expense, gross	$ 2,103	$ 1,900
Performance-based Shares [Member]
Restricted and Performance Stock Grants [Abstract]
Measuring period for performance-based shares	3 years
Restricted Shares [Member] \| Employees [Member]
Restricted and Performance Stock Grants [Abstract]
Estimated forfeitures	5.00%
Restricted Shares [Member] \| Executives [Member]
Restricted and Performance Stock Grants [Abstract]
Estimated forfeitures	0.00%
Restricted Shares [Member] \| Directors [Member]
Restricted and Performance Stock Grants [Abstract]
Estimated forfeitures	0.00%
Restricted Shares [Member] \| Age 60 [Member]
Restricted and Performance Stock Grants [Abstract]
Vesting percentage	25.00%
Restricted Shares [Member] \| Age 63 [Member]
Restricted and Performance Stock Grants [Abstract]
Vesting percentage	25.00%
Restricted Shares [Member] \| Age 65 [Member]
Restricted and Performance Stock Grants [Abstract]
Vesting percentage	100.00%
Restricted and Performance-Based Shares [Member]
Restricted and performance-based stock, shares [Roll Forward]
Beginning of period (in shares)	852,540
Granted (in shares)	0
Vested (in shares)	(32,793)
Forfeited (in shares)	(5,950)
End of period (in shares)	813,797
Restricted and performance-based stock, weighted average grant date fair value per share [Roll Forward]
Beginning of period (in dollars per share)	$ 35.26
Granted (in dollars per share)	0
Vested (in dollars per share)	34.04
Forfeited (in dollars per share)	43.70
End of period (in dollars per share)	$ 35.28
Additional Disclosures [Abstract]
Compensation expense, gross	$ 2,100	1,900
Compensation expense, net of tax	1,600	$ 1,400
Unamortized compensation expense	$ 13,900
Restricted and Performance-Based Shares [Member] \| Employees [Member]
Additional Disclosures [Abstract]
Weighted average period of recognition for unrecognized compensation expense	4 years 4 months 24 days
Restricted and Performance-Based Shares [Member] \| Directors [Member]
Additional Disclosures [Abstract]
Weighted average period of recognition for unrecognized compensation expense	29 days
Restricted and Performance-Based Shares [Member] \| Executives and Directors [Member]
Restricted and Performance Stock Grants [Abstract]
Expiration of vesting period	3 years
Restricted and Performance-Based Shares [Member] \| Executives and Directors [Member] \| Minimum [Member]
Restricted and Performance Stock Grants [Abstract]
Post vesting holding period for restricted and performance shares issued	1 year
Restricted and Performance-Based Shares [Member] \| Executives and Directors [Member] \| Maximum [Member]
Restricted and Performance Stock Grants [Abstract]
Post vesting holding period for restricted and performance shares issued	2 years

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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