Loans (Past Due Loans) (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		$ 14,700	$ 13,622
Current		3,723,769	3,666,738
Total loans	[1]	3,738,469	3,680,360
30-59
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		7,733	7,787
60-89
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		3,182	3,774
Over 90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		3,785	2,061
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		926	1,080
Current		1,462,756	1,391,328
Total loans	[2]	1,463,682	1,392,408
Commercial Real Estate | 30-59
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	155
Commercial Real Estate | 60-89
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	925
Commercial Real Estate | Over 90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		926	0
Commercial & Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1	0
Current		610,607	620,704
Total loans	[3]	610,608	620,704
Commercial & Industrial | 30-59
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1	0
Commercial & Industrial | 60-89
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
Commercial & Industrial | Over 90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
Total Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		927	1,080
Current		2,073,363	2,012,032
Total loans		2,074,290	2,013,112
Total Commercial | 30-59
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1	155
Total Commercial | 60-89
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	925
Total Commercial | Over 90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		926	0
Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		10,849	10,520
Current		1,348,223	1,349,867
Total loans	[4]	1,359,072	1,360,387
Residential Real Estate | 30-59
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		5,868	6,318
Residential Real Estate | 60-89
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		2,749	2,693
Residential Real Estate | Over 90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		2,232	1,509
Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		2,911	1,989
Current		277,027	278,637
Total loans		279,938	280,626
Home Equity | 30-59
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1,851	1,281
Home Equity | 60-89
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		433	156
Home Equity | Over 90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		627	552
Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		13	33
Current		25,156	26,202
Total loans	[5]	25,169	26,235
Other | 30-59
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		13	33
Other | 60-89
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
Other | Over 90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		0	0
Total Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		2,924	2,022
Current		302,183	304,839
Total loans		305,107	306,861
Total Consumer | 30-59
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1,864	1,314
Total Consumer | 60-89
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		433	156
Total Consumer | Over 90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		$ 627	$ 552

[1] Includes net unamortized loan origination costs of $4.9 million and $4.7 million, respectively, at March 31, 2019 and December 31, 2018 and net unamortized premiums on purchased loans of $668 thousand and $703 thousand, respectively, at March 31, 2019 and December 31, 2018.

[2] Consists of commercial mortgages primarily secured by income-producing property, as well as construction and development loans. Construction and development loans are made to businesses for land development or the on-site construction of industrial, commercial, or residential buildings.

[3] Consists of loans to businesses and individuals, a substantial portion of which are fully or partially collateralized by real estate.

[4] Consists of mortgage and homeowner construction loans secured by one- to four-family residential properties.

[5] Consists of loans to individuals secured by general aviation aircraft and other personal installment loans.