Loans and Allowance for Credit Losses (Details 5) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Loans past due	$ 30,249	$ 31,082	$ 28,650
Current loans	6,053,955	5,646,811	5,453,325
Total recorded investment in loans	6,084,204	5,677,893	5,481,975
Real Estate Mortgage - Residential Portfolio Segment [Member]
Loans past due	3,904	1,733	726
Current loans	105,556	151,015	153,713
Total recorded investment in loans	109,460	152,748	154,439
Commercial Real Estate - Owner Occupied Portfolio Segment [Member]
Loans past due	10,655	9,408	5,441
Current loans	738,925	631,462	584,986
Total recorded investment in loans	749,580	640,870	590,427
Other Consumer Portfolio Segment [Member]
Loans past due	117	236	24
Current loans	8,696	10,129	6,188
Total recorded investment in loans	8,813	10,365	6,212
Commercial Real Estate - Income Producing Portfolio Segment [Member]
Loans past due	4,810	11,050	10,098
Current loans	2,894,138	2,498,467	2,541,088
Total recorded investment in loans	2,898,948	2,509,517	2,551,186
Home Equity Portfolio Segment [Member]
Loans past due	1,331		1,295
Current loans	100,567	105,096	105,561
Total recorded investment in loans	101,898	105,096	106,856
Construction Portfolio Segment [Member]
Loans past due	5,127	3,774	6,412
Current loans	966,194	1,054,795	936,401
Total recorded investment in loans	971,321	1,058,569	942,813
Commercial Portfolio Segment [Member]
Loans past due	4,305	4,881	4,654
Current loans	1,239,879	1,195,847	1,125,388
Total recorded investment in loans	1,244,184	1,200,728	1,130,042
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	6,713	7,608	1,743
Financing Receivables, 30 to 59 Days Past Due [Member] | Real Estate Mortgage - Residential Portfolio Segment [Member]
Loans past due	1,480	1,015
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate - Owner Occupied Portfolio Segment [Member]
Loans past due	817	3,987
Financing Receivables, 30 to 59 Days Past Due [Member] | Other Consumer Portfolio Segment [Member]
Loans past due	21	101	8
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate - Income Producing Portfolio Segment [Member]
Loans past due	3,160	511
Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity Portfolio Segment [Member]
Loans past due	637		562
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction Portfolio Segment [Member]
Loans past due	197	360
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans past due	401	1,634	1,173
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	6,927	5,599	4,633
Financing Receivables, 60 to 89 Days Past Due [Member] | Real Estate Mortgage - Residential Portfolio Segment [Member]
Loans past due	2,123	163	164
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate - Owner Occupied Portfolio Segment [Member]
Loans past due	3,268	3,328	3,338
Financing Receivables, 60 to 89 Days Past Due [Member] | Other Consumer Portfolio Segment [Member]
Loans past due	4	9	16
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate - Income Producing Portfolio Segment [Member]
Loans past due	770
Financing Receivables, 60 to 89 Days Past Due [Member] | Home Equity Portfolio Segment [Member]
Loans past due	100		620
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction Portfolio Segment [Member]
Loans past due		1,342
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans past due	662	757	495
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	16,609	17,875	22,274
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate Mortgage - Residential Portfolio Segment [Member]
Loans past due	301	555	562
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate - Owner Occupied Portfolio Segment [Member]
Loans past due	6,570	2,093	2,103
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Other Consumer Portfolio Segment [Member]
Loans past due	92	126
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate - Income Producing Portfolio Segment [Member]
Loans past due	880	10,539	10,098
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home Equity Portfolio Segment [Member]
Loans past due	594		113
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction Portfolio Segment [Member]
Loans past due	4,930	2,072	6,412
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Loans past due	$ 3,242	$ 2,490	$ 2,986