Parent Company Financial Information (Details 1) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gain on sale of investment securities													$ 542	$ 1,194	$ 2,254
Interest expense	$ 11,167	$ 10,434	$ 9,646	$ 8,900	$ 8,771	$ 7,703	$ 5,950	$ 5,216	$ 4,735	$ 4,896	$ 4,873	$ 4,734	40,147	27,640	19,238
Legal and professional													5,053	3,673	3,729
Other													15,869	15,255	15,636
Income Tax Expense	35,396	17,409	17,382	15,318	16,429	15,484	15,069	14,413	13,485	13,054	12,776	11,734	85,504	61,395	51,049
Net Income	15,569	29,874	27,772	27,017	25,717	24,523	24,145	23,322	22,348	21,463	20,938	19,418	100,232	97,707	84,167
Preferred Stock Dividends										180	179	180			601
Net income available to common shareholders	$ 15,569	$ 29,874	$ 27,772	$ 27,017	$ 25,717	$ 24,523	$ 24,145	$ 23,322	$ 22,286	$ 21,283	$ 20,759	$ 19,238	100,232	97,707	83,566
Parent Company [Member]
Other interest and dividends													234	280	369
Gain on sale of investment securities														43	60
Total Income													234	323	429
Interest expense													11,916	7,493	4,490
Legal and professional													118	131	101
Directors compensation													352	202	224
Other													1,246	1,083	1,212
Total Expenses													13,632	8,909	6,027
Income Before Income Tax Expense													(13,398)	(8,586)	(5,598)
Income Tax Expense													(4,689)	(2,919)	(2,208)
Loss Before Equity in Undistributed Income of Subsidiaries													(8,709)	(5,667)	(3,390)
Equity in Undistributed Income of Subsidiaries													108,941	103,374	87,557
Net Income													100,232	97,707	84,167
Preferred Stock Dividends															601
Net income available to common shareholders													$ 100,232	$ 97,707	$ 83,566