Business Segments (Statement of Operations and Total Assets by Reportable Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net interest income (expense)	$ 33,111	$ 29,904	$ 64,963	$ 58,583
Provision for loan losses	400	700	400	1,100
Net interest income after provision for loan losses	32,711	29,204	64,563	57,483
Noninterest income	15,993	16,806	31,736	31,316
Depreciation and amortization expense	1,050	1,115	2,125	2,293
Other noninterest expenses related to segments	25,238	25,191	51,293	49,299
Total noninterest expense	26,288	26,306	53,418	51,592
Income before income taxes	22,416	19,704	42,881	37,207
Income tax expense	4,742	6,505	8,996	12,226
Net income	17,674	13,199	33,885	24,981
Total assets	4,737,242	4,375,529	4,737,242	4,375,529	$ 4,529,850
Expenditures for long-lived assets	864	514	1,675	1,247
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	26,644	24,633	52,620	48,190
Provision for loan losses	400	700	400	1,100
Net interest income after provision for loan losses	26,244	23,933	52,220	47,090
Noninterest income	5,837	6,347	10,773	10,789
Depreciation and amortization expense	637	651	1,274	1,314
Other noninterest expenses related to segments	15,509	15,323	30,975	29,930
Total noninterest expense	16,146	15,974	32,249	31,244
Income before income taxes	15,935	14,306	30,744	26,635
Income tax expense	3,387	4,650	6,490	8,679
Net income	12,548	9,656	24,254	17,956
Total assets	3,647,649	3,346,184	3,647,649	3,346,184
Expenditures for long-lived assets	801	377	1,252	750
Wealth Management Services [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	(77)	(40)	(135)	(72)
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	(77)	(40)	(135)	(72)
Noninterest income	9,602	9,942	19,875	19,419
Depreciation and amortization expense	370	414	766	877
Other noninterest expenses related to segments	6,593	6,848	13,792	13,296
Total noninterest expense	6,963	7,262	14,558	14,173
Income before income taxes	2,562	2,640	5,182	5,174
Income tax expense	655	1,102	1,298	2,080
Net income	1,907	1,538	3,884	3,094
Total assets	68,009	66,286	68,009	66,286
Expenditures for long-lived assets	11	41	313	343
Corporate [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	6,544	5,311	12,478	10,465
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	6,544	5,311	12,478	10,465
Noninterest income	554	517	1,088	1,108
Depreciation and amortization expense	43	50	85	102
Other noninterest expenses related to segments	3,136	3,020	6,526	6,073
Total noninterest expense	3,179	3,070	6,611	6,175
Income before income taxes	3,919	2,758	6,955	5,398
Income tax expense	700	753	1,208	1,467
Net income	3,219	2,005	5,747	3,931
Total assets	1,021,584	963,059	1,021,584	963,059
Expenditures for long-lived assets	$ 52	$ 96	$ 110	$ 154