Loans and Allowance for Credit Losses (Details 3) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Loans and leases receivable, net of deferred income	$ 6,084,204	$ 5,677,893	$ 5,481,975
Real Estate Mortgage - Residential Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	109,460	152,748	154,439
Commercial Real Estate - Owner Occupied Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	749,580	640,870	590,427
Other Consumer Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	8,813	10,365	6,212
Commercial Real Estate - Income Producing Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	2,898,948	2,509,517	2,551,186
Home Equity Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	101,898	105,096	106,856
Construction Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	971,321	1,058,569	942,813
Commercial Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	1,244,184	1,200,728	1,130,042
Pass [Member]
Loans and leases receivable, net of deferred income	5,968,616	5,597,416	5,407,185
Pass [Member] | Real Estate Mortgage - Residential Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	108,797	151,831	153,515
Pass [Member] | Commercial Real Estate - Owner Occupied Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	720,693	630,827	577,925
Pass [Member] | Other Consumer Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	8,719	10,237	6,209
Pass [Member] | Commercial Real Estate - Income Producing Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	2,861,346	2,489,407	2,527,318
Pass [Member] | Home Equity Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	100,618	103,484	105,126
Pass [Member] | Construction Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	963,593	1,051,445	937,198
Pass [Member] | Commercial Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	1,204,850	1,160,185	1,099,894
Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	82,054	46,006	41,255
Watch and Special Mention [Member] | Real Estate Mortgage - Residential Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	663	676	680
Watch and Special Mention [Member] | Commercial Real Estate - Owner Occupied Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	22,317	7,950	10,399
Watch and Special Mention [Member] | Other Consumer Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	2	2	3
Watch and Special Mention [Member] | Commercial Real Estate - Income Producing Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	27,361	5,053	9,220
Watch and Special Mention [Member] | Home Equity Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	686	1,612	1,617
Watch and Special Mention [Member] | Construction Portfolio Segment [Member]
Loans and leases receivable, net of deferred income		607	737
Watch and Special Mention [Member] | Commercial Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	31,025	30,106	18,599
Substandard [Member]
Loans and leases receivable, net of deferred income	33,534	34,471	33,535
Substandard [Member] | Real Estate Mortgage - Residential Portfolio Segment [Member]
Loans and leases receivable, net of deferred income		241	244
Substandard [Member] | Commercial Real Estate - Owner Occupied Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	6,570	2,093	2,103
Substandard [Member] | Other Consumer Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	92	126
Substandard [Member] | Commercial Real Estate - Income Producing Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	10,241	15,057	14,648
Substandard [Member] | Home Equity Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	594		113
Substandard [Member] | Construction Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	7,728	6,517	4,878
Substandard [Member] | Commercial Portfolio Segment [Member]
Loans and leases receivable, net of deferred income	$ 8,309	$ 10,437	$ 11,549