Parent Only Financial Information Parent Only Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Interest and Dividends on Investments	$ 96,503	$ 84,657	$ 76,915
Other Operating Income	1,324	927	1,113
Interest Expense	12,485	7,006	5,356
Other Operating Expense	15,599	14,577	14,494
Provision for Income Taxes	9,026	10,529	11,215
Net Income	36,279	29,326	26,534
Parent Company
Condensed Financial Statements, Captions [Line Items]
Dividends from Bank Subsidiaries	13,300	12,800	11,650
Interest and Dividends on Investments	48	53	117
Other Operating Income	907	677	635
Total Income	14,255	13,530	12,402
Interest Expense	976	781	691
Other Operating Expense	1,175	958	942
Total Expense	2,151	1,739	1,633
Income Before Income Tax Benefit and Equity in Undistributed Net Income of Subsidiaries	12,104	11,791	10,769
Provision for Income Taxes	686	225	482
Equity in Undistributed Net Income of Subsidiaries	23,489	17,310	15,283
Net Income	$ 36,279	$ 29,326	$ 26,534