Loans and Allowance for Credit Losses (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Allowance for Credit Losses, beginning balance	$ 66,609	$ 61,047	$ 64,758	$ 59,074
Loans charged-off	(1,832)	(593)	(3,863)	(2,266)
Recoveries of loans previously charged-off	971	592	1,234	1,275
Net loans charged-off	(861)	(1)	(2,629)	(991)
Provision for credit losses	2,441	1,921	6,060	4,884
Allowance for Credit Losses, ending balance	68,189	62,967	68,189	62,967
Individually evaluated for impairment	9,870	8,700	9,870	8,700
Collectively evaluated for impairment	58,319	54,267	58,319	54,267
Commercial [Member]
Allowance for Credit Losses, beginning balance	12,206	14,225	13,102	14,700
Loans charged-off	(1,174)	(522)	(2,435)	(659)
Recoveries of loans previously charged-off	60	407	86	675
Net loans charged-off	(1,114)	(115)	(2,349)	16
Provision for credit losses	4,557	(2,266)	4,896	(2,872)
Allowance for Credit Losses, ending balance	15,649	11,844	15,649	11,844
Individually evaluated for impairment	6,271	3,246	6,271	3,246
Collectively evaluated for impairment	9,378	8,598	9,378	8,598
Income Producing - Commercial Real Estate [Member]
Allowance for Credit Losses, beginning balance	27,988	23,308	25,376	21,105
Loans charged-off			(121)	(1,470)
Recoveries of loans previously charged-off		30	2	80
Net loans charged-off		30	(119)	(1,390)
Provision for credit losses	(601)	(963)	2,130	2,660
Allowance for Credit Losses, ending balance	27,387	22,375	27,387	22,375
Individually evaluated for impairment	3,043	1,378	3,043	1,378
Collectively evaluated for impairment	24,344	20,997	24,344	20,997
Owner Occupied - Commercial Real Estate - [Member]
Allowance for Credit Losses, beginning balance	6,003	4,189	5,934	4,010
Loans charged-off			(132)
Recoveries of loans previously charged-off			2	2
Net loans charged-off			(130)	2
Provision for credit losses	(72)	1,273	127	1,450
Allowance for Credit Losses, ending balance	5,931	5,462	5,931	5,462
Individually evaluated for impairment	500	1,005	500	1,005
Collectively evaluated for impairment	5,431	4,457	5,431	4,457
Real Estate Mortgage - Residential [Member]
Allowance for Credit Losses, beginning balance	757	1,081	944	1,284
Loans charged-off
Recoveries of loans previously charged-off	1	2	4	5
Net loans charged-off	1	2	4	5
Provision for credit losses	(9)	(126)	(199)	(332)
Allowance for Credit Losses, ending balance	749	957	749	957
Individually evaluated for impairment
Collectively evaluated for impairment	749	957	749	957
Construction - Commercial And Residential [Member]
Allowance for Credit Losses, beginning balance	18,651	16,727	18,492	16,487
Loans charged-off	(643)	(39)	(1,160)	(39)
Recoveries of loans previously charged-off	899	146	994	491
Net loans charged-off	256	107	(166)	452
Provision for credit losses	(1,368)	4,052	(787)	3,947
Allowance for Credit Losses, ending balance	17,539	20,886	17,539	20,886
Individually evaluated for impairment		2,900		2,900
Collectively evaluated for impairment	17,539	17,986	17,539	17,986
Home Equity [Member]
Allowance for Credit Losses, beginning balance	673	1,216	770	1,328
Loans charged-off
Recoveries of loans previously charged-off	6	1	133	4
Net loans charged-off	6	1	133	4
Provision for credit losses	(48)	(120)	(272)	(235)
Allowance for Credit Losses, ending balance	631	1,097	631	1,097
Individually evaluated for impairment		90		90
Collectively evaluated for impairment	631	1,007	631	1,007
Other Consumer [Member]
Allowance for Credit Losses, beginning balance	331	301	140	160
Loans charged-off	(15)	(32)	(15)	(98)
Recoveries of loans previously charged-off	5	6	13	18
Net loans charged-off	(10)	(26)	(2)	(80)
Provision for credit losses	(18)	71	165	266
Allowance for Credit Losses, ending balance	303	346	303	346
Individually evaluated for impairment	56	81	56	81
Collectively evaluated for impairment	$ 247	$ 265	$ 247	$ 265