Business Segments (Statement of Operations and Total Assets by Reportable Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net interest income (expense)	$ 32,978	$ 33,449	$ 101,420	$ 98,412
Provision for loan losses	400	350	1,575	750
Net interest income after provision for loan losses	32,578	33,099	99,845	97,662
Noninterest income	18,342	15,215	50,462	46,951
Depreciation and amortization expense	1,042	1,069	3,192	3,194
Other noninterest expenses related to segments	25,828	24,993	78,793	76,286
Total noninterest expense	26,870	26,062	81,985	79,480
Income before income taxes	24,050	22,252	68,322	65,133
Income tax expense	5,236	4,741	14,740	13,737
Net income	18,814	17,511	53,582	51,396
Total assets	5,198,878	4,770,672	5,198,878	4,770,672	$ 5,010,766
Expenditures for long-lived assets	797	645	2,768	2,320
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	28,515	27,036	83,684	79,656
Provision for loan losses	400	350	1,575	750
Net interest income after provision for loan losses	28,115	26,686	82,109	78,906
Noninterest income	8,607	5,174	20,753	15,947
Depreciation and amortization expense	642	654	1,985	1,928
Other noninterest expenses related to segments	16,255	15,599	48,676	46,574
Total noninterest expense	16,897	16,253	50,661	48,502
Income before income taxes	19,825	15,607	52,201	46,351
Income tax expense	4,347	3,344	11,371	9,834
Net income	15,478	12,263	40,830	36,517
Total assets	3,994,458	3,694,991	3,994,458	3,694,991
Expenditures for long-lived assets	662	612	2,259	1,864
Wealth Management Services [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	(114)	(90)	(361)	(225)
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	(114)	(90)	(361)	(225)
Noninterest income	9,153	9,454	27,961	29,329
Depreciation and amortization expense	360	371	1,089	1,137
Other noninterest expenses related to segments	6,217	6,194	19,631	19,986
Total noninterest expense	6,577	6,565	20,720	21,123
Income before income taxes	2,462	2,799	6,880	7,981
Income tax expense	646	710	1,845	2,008
Net income	1,816	2,089	5,035	5,973
Total assets	78,812	69,494	78,812	69,494
Expenditures for long-lived assets	87	14	379	327
Corporate [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	4,577	6,503	18,097	18,981
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	4,577	6,503	18,097	18,981
Noninterest income	582	587	1,748	1,675
Depreciation and amortization expense	40	44	118	129
Other noninterest expenses related to segments	3,356	3,200	10,486	9,726
Total noninterest expense	3,396	3,244	10,604	9,855
Income before income taxes	1,763	3,846	9,241	10,801
Income tax expense	243	687	1,524	1,895
Net income	1,520	3,159	7,717	8,906
Total assets	1,125,608	1,006,187	1,125,608	1,006,187
Expenditures for long-lived assets	$ 48	$ 19	$ 130	$ 129