Loans and Allowance for Credit Losses (Details 3) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans and leases receivable, net of deferred income	$ 6,602,526	$ 6,411,528
Pass [Member]
Loans and leases receivable, net of deferred income	6,492,140	6,288,782
Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	71,010	92,555
Substandard [Member]
Loans and leases receivable, net of deferred income	39,376	30,191
Commercial [Member]
Loans and leases receivable, net of deferred income	1,426,042	1,375,939
Commercial [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	1,381,816	1,333,050
Commercial [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	28,758	34,163
Commercial [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	15,468	8,726
Income Producing - Commercial Real Estate [Member]
Loans and leases receivable, net of deferred income	3,137,498	3,047,094
Income Producing - Commercial Real Estate [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	3,123,614	3,033,046
Income Producing - Commercial Real Estate [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	4,490	3,856
Income Producing - Commercial Real Estate [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	9,394	10,192
Owner Occupied - Commercial Real Estate - [Member]
Loans and leases receivable, net of deferred income	800,747	755,444
Owner Occupied - Commercial Real Estate - [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	756,551	696,754
Owner Occupied - Commercial Real Estate - [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	36,425	53,189
Owner Occupied - Commercial Real Estate - [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	7,771	5,501
Real Estate Mortgage - Residential [Member]
Loans and leases receivable, net of deferred income	103,932	104,357
Real Estate Mortgage - Residential [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	101,831	103,220
Real Estate Mortgage - Residential [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	650	659
Real Estate Mortgage - Residential [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	1,451	478
Construction - Commercial And Residencial [Member]
Loans and leases receivable, net of deferred income	1,040,813	1,031,832
Construction - Commercial And Residencial [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	1,036,106	1,027,123
Construction - Commercial And Residencial [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income
Construction - Commercial And Residencial [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	4,707	4,709
Home Equity [Member]
Loans and leases receivable, net of deferred income	90,271	93,264
Home Equity [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	89,091	92,084
Home Equity [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	686	686
Home Equity [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	494	494
Other Consumer [Member]
Loans and leases receivable, net of deferred income	3,223	3,598
Other Consumer [Member] | Pass [Member]
Loans and leases receivable, net of deferred income	3,131	3,505
Other Consumer [Member] | Watch and Special Mention [Member]
Loans and leases receivable, net of deferred income	1	2
Other Consumer [Member] | Substandard [Member]
Loans and leases receivable, net of deferred income	$ 91	$ 91