Business Segments (Statement of Operations and Total Assets by Reportable Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net interest income (expense)	$ 33,449	$ 30,059	$ 98,412	$ 88,642
Provision for loan losses	350	1,300	750	2,400
Net interest income after provision for loan losses	33,099	28,759	97,662	86,242
Noninterest income	15,215	17,283	46,951	48,599
Depreciation and amortization expense	1,069	1,107	3,194	3,400
Other noninterest expenses related to segments	24,993	25,647	76,286	74,946
Total noninterest expense	26,062	26,754	79,480	78,346
Income before income taxes	22,252	19,288	65,133	56,495
Income tax expense	4,741	6,326	13,737	18,552
Net income	17,511	12,962	51,396	37,943
Total assets	4,770,672	4,469,230	4,770,672	4,469,230	$ 4,529,850
Expenditures for long-lived assets	645	937	2,320	2,184
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	27,036	24,795	79,656	72,985
Provision for loan losses	350	1,300	750	2,400
Net interest income after provision for loan losses	26,686	23,495	78,906	70,585
Noninterest income	5,174	6,711	15,947	17,500
Depreciation and amortization expense	654	646	1,928	1,960
Other noninterest expenses related to segments	15,599	15,834	46,574	45,764
Total noninterest expense	16,253	16,480	48,502	47,724
Income before income taxes	15,607	13,726	46,351	40,361
Income tax expense	3,344	4,463	9,834	13,142
Net income	12,263	9,263	36,517	27,219
Total assets	3,694,991	3,486,783	3,694,991	3,486,783
Expenditures for long-lived assets	612	890	1,864	1,640
Wealth Management Services [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	(90)	(48)	(225)	(120)
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	(90)	(48)	(225)	(120)
Noninterest income	9,454	10,013	29,329	29,432
Depreciation and amortization expense	371	411	1,137	1,288
Other noninterest expenses related to segments	6,194	6,810	19,986	20,106
Total noninterest expense	6,565	7,221	21,123	21,394
Income before income taxes	2,799	2,744	7,981	7,918
Income tax expense	710	1,092	2,008	3,172
Net income	2,089	1,652	5,973	4,746
Total assets	69,494	63,600	69,494	63,600
Expenditures for long-lived assets	14	25	327	368
Corporate [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	6,503	5,312	18,981	15,777
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	6,503	5,312	18,981	15,777
Noninterest income	587	559	1,675	1,667
Depreciation and amortization expense	44	50	129	152
Other noninterest expenses related to segments	3,200	3,003	9,726	9,076
Total noninterest expense	3,244	3,053	9,855	9,228
Income before income taxes	3,846	2,818	10,801	8,216
Income tax expense	687	771	1,895	2,238
Net income	3,159	2,047	8,906	5,978
Total assets	1,006,187	918,847	1,006,187	918,847
Expenditures for long-lived assets	$ 19	$ 22	$ 129	$ 176