Loans and Allowance for Credit Losses (Details 3) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans and leases receivable, net of deferred income	$ 6,411,528	$ 5,677,893
Pass [Member]
Loans and leases receivable, net of deferred income	6,288,782	5,597,416
Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	92,555	46,006
Substandard [Member]
Loans and leases receivable, net of deferred income	30,191	34,471
Commercial [Member]
Loans and leases receivable, net of deferred income	1,375,939	1,200,728
Commercial [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	1,333,050	1,160,185
Commercial [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	34,163	30,106
Commercial [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	8,726	10,437
Income Producing - Commercial Real Estate [Member]
Loans and leases receivable, net of deferred income	3,047,094	2,509,517
Income Producing - Commercial Real Estate [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	3,033,046	2,489,407
Income Producing - Commercial Real Estate [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	3,856	5,053
Income Producing - Commercial Real Estate [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	10,192	15,057
Owner Occupied - Commercial Real Estate - [Member]
Loans and leases receivable, net of deferred income	755,444	640,870
Owner Occupied - Commercial Real Estate - [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	696,754	630,827
Owner Occupied - Commercial Real Estate - [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	53,189	7,950
Owner Occupied - Commercial Real Estate - [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	5,501	2,093
Real Estate Mortgage - Residential [Member]
Loans and leases receivable, net of deferred income	104,357	152,748
Real Estate Mortgage - Residential [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	103,220	151,831
Real Estate Mortgage - Residential [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	659	676
Real Estate Mortgage - Residential [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	478	241
Construction - Commercial And Residencial [Member]
Loans and leases receivable, net of deferred income	1,031,832	1,058,569
Construction - Commercial And Residencial [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	1,027,123	1,051,445
Construction - Commercial And Residencial [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income		607
Construction - Commercial And Residencial [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	4,709	6,517
Home Equity [Member]
Loans and leases receivable, net of deferred income	93,264	105,096
Home Equity [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	92,084	103,484
Home Equity [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	686	1,612
Home Equity [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	494
Other Consumer [Member]
Loans and leases receivable, net of deferred income	3,598	10,365
Other Consumer [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	3,505	10,237
Other Consumer [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	2	2
Other Consumer [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	$ 91	$ 126