Loans (Past Due Loans) (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Total past due		$ 14,356	$ 13,622
Current		3,763,750	3,666,738
Total loans	[1]	3,778,106	3,680,360
30-59
Financing Receivable, Past Due [Line Items]
Total past due		5,089	7,787
60-89
Financing Receivable, Past Due [Line Items]
Total past due		2,923	3,774
Over 90
Financing Receivable, Past Due [Line Items]
Total past due		6,344	2,061
Commercial Real Estate
Financing Receivable, Past Due [Line Items]
Total past due		684	1,080
Current		1,516,636	1,391,328
Total loans	[2]	1,517,320	1,392,408
Commercial Real Estate | 30-59
Financing Receivable, Past Due [Line Items]
Total past due		0	155
Commercial Real Estate | 60-89
Financing Receivable, Past Due [Line Items]
Total past due		0	925
Commercial Real Estate | Over 90
Financing Receivable, Past Due [Line Items]
Total past due		684	0
Commercial & Industrial
Financing Receivable, Past Due [Line Items]
Total past due		1	0
Current		566,425	620,704
Total loans	[3]	566,426	620,704
Commercial & Industrial | 30-59
Financing Receivable, Past Due [Line Items]
Total past due		1	0
Commercial & Industrial | 60-89
Financing Receivable, Past Due [Line Items]
Total past due		0	0
Commercial & Industrial | Over 90
Financing Receivable, Past Due [Line Items]
Total past due		0	0
Total Commercial
Financing Receivable, Past Due [Line Items]
Total past due		685	1,080
Current		2,083,061	2,012,032
Total loans		2,083,746	2,013,112
Total Commercial | 30-59
Financing Receivable, Past Due [Line Items]
Total past due		1	155
Total Commercial | 60-89
Financing Receivable, Past Due [Line Items]
Total past due		0	925
Total Commercial | Over 90
Financing Receivable, Past Due [Line Items]
Total past due		684	0
Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total past due		11,599	10,520
Current		1,366,919	1,349,867
Total loans	[4]	1,378,518	1,360,387
Residential Real Estate | 30-59
Financing Receivable, Past Due [Line Items]
Total past due		4,333	6,318
Residential Real Estate | 60-89
Financing Receivable, Past Due [Line Items]
Total past due		2,506	2,693
Residential Real Estate | Over 90
Financing Receivable, Past Due [Line Items]
Total past due		4,760	1,509
Home Equity
Financing Receivable, Past Due [Line Items]
Total past due		1,973	1,989
Current		292,277	278,637
Total loans		294,250	280,626
Home Equity | 30-59
Financing Receivable, Past Due [Line Items]
Total past due		744	1,281
Home Equity | 60-89
Financing Receivable, Past Due [Line Items]
Total past due		417	156
Home Equity | Over 90
Financing Receivable, Past Due [Line Items]
Total past due		812	552
Other
Financing Receivable, Past Due [Line Items]
Total past due		99	33
Current		21,493	26,202
Total loans	[5]	21,592	26,235
Other | 30-59
Financing Receivable, Past Due [Line Items]
Total past due		11	33
Other | 60-89
Financing Receivable, Past Due [Line Items]
Total past due		0	0
Other | Over 90
Financing Receivable, Past Due [Line Items]
Total past due		88	0
Total Consumer
Financing Receivable, Past Due [Line Items]
Total past due		2,072	2,022
Current		313,770	304,839
Total loans		315,842	306,861
Total Consumer | 30-59
Financing Receivable, Past Due [Line Items]
Total past due		755	1,314
Total Consumer | 60-89
Financing Receivable, Past Due [Line Items]
Total past due		417	156
Total Consumer | Over 90
Financing Receivable, Past Due [Line Items]
Total past due		$ 900	$ 552

[1] Includes net unamortized loan origination costs of $5.7 million and $4.7 million, respectively, at September 30, 2019 and December 31, 2018 and net unamortized premiums on purchased loans of $575 thousand and $703 thousand, respectively, at September 30, 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.