Income Taxes (Details 1) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Line Items]
Tax expense at statutory rate (21%-2018 35%-2017 and 2016)									$ 11,944	$ 16,958	$ 14,559
Increases (decreases) in taxes from:
State income tax - net of federal tax benefit									164	119	159
Tax exempt interest income, net of TEFRA									(770)	(1,218)	(1,168)
Bank owned life insurance									(255)	(1,212)	(341)
Captive insurance									(325)	(364)	(414)
BOLI surrender									0	1,721	0
Tax reform revaluation									0	154	0
Other									(132)	26	(41)
Totals	$ 3,082	$ 2,483	$ 2,564	$ 2,497	$ 4,431	$ 4,219	$ 3,677	$ 3,857	$ 10,626	$ 16,184	$ 12,754