Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reconciliation of Federal Statutory to Actual Tax Expense:
Federal statutory income tax at 21% for 2018 and 35% for 2017	$ 10,414	$ 11,304	$ 29,500	$ 32,900
Tax-exempt interest income	(2,118)	(2,881)	(6,178)	(8,062)
Share-based compensation	(38)	(78)	(570)	(862)
Tax-exempt earnings and gains on life insurance	(197)	(551)	(655)	(1,905)
Tax credits	(42)	(61)	(65)	(249)
Other	459	206	1,018	492
Actual Tax Expense	$ 8,478	$ 7,939	$ 23,050	$ 22,314
Federal statutory income tax rate	21.00%	35.00%	21.00%	35.00%
Effective Tax Rate	17.10%	24.60%	16.40%	23.70%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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