Allowance for Credit Losses and Credit Quality of Loans, Credit Quality by Loan Class (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Credit Quality by Loan Class [Abstract]
Net loans	$ 7,247,383	$ 7,136,098
Originated [Member]
Credit Quality by Loan Class [Abstract]
Net loans		6,871,220
Originated [Member] | Commercial Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans		2,790,472
Originated [Member] | Commercial Credit Exposure [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans		2,651,441
Originated [Member] | Commercial Credit Exposure [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans		58,899
Originated [Member] | Commercial Credit Exposure [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans		79,626
Originated [Member] | Commercial Credit Exposure [Member] | C&I [Member]
Credit Quality by Loan Class [Abstract]
Net loans		840,906
Originated [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans		782,763
Originated [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans		28,380
Originated [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans		29,257
Originated [Member] | Commercial Credit Exposure [Member] | CRE [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,949,566
Originated [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,868,678
Originated [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans		30,519
Originated [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans		50,369
Originated [Member] | Business Banking Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans		538,528
Originated [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans		524,725
Originated [Member] | Business Banking Credit Exposure [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans		13,803
Originated [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member]
Credit Quality by Loan Class [Abstract]
Net loans		538,528
Originated [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans		524,725
Originated [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans		13,803
Originated [Member] | Consumer Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans		2,222,943
Originated [Member] | Consumer Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		2,215,503
Originated [Member] | Consumer Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		7,440
Originated [Member] | Consumer Credit Exposure [Member] | Indirect Auto [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,193,635
Originated [Member] | Consumer Credit Exposure [Member] | Indirect Auto [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,190,455
Originated [Member] | Consumer Credit Exposure [Member] | Indirect Auto [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		3,180
Originated [Member] | Consumer Credit Exposure [Member] | Specialty Lending [Member]
Credit Quality by Loan Class [Abstract]
Net loans		542,063
Originated [Member] | Consumer Credit Exposure [Member] | Specialty Lending [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		540,756
Originated [Member] | Consumer Credit Exposure [Member] | Specialty Lending [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,307
Originated [Member] | Consumer Credit Exposure [Member] | Direct [Member]
Credit Quality by Loan Class [Abstract]
Net loans		487,245
Originated [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		484,292
Originated [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		2,953
Originated [Member] | Residential Real Estate Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,319,277
Originated [Member] | Residential Real Estate Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,312,742
Originated [Member] | Residential Real Estate Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		6,535
Originated [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,319,277
Originated [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,312,742
Originated [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		6,535
Acquired [Member]
Credit Quality by Loan Class [Abstract]
Net loans		264,878
Acquired [Member] | Commercial Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans		80,301
Acquired [Member] | Commercial Credit Exposure [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans		78,346
Acquired [Member] | Commercial Credit Exposure [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,269
Acquired [Member] | Commercial Credit Exposure [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans		686
Acquired [Member] | Commercial Credit Exposure [Member] | C&I [Member]
Credit Quality by Loan Class [Abstract]
Net loans		19,364
Acquired [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans		17,801
Acquired [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,269
Acquired [Member] | Commercial Credit Exposure [Member] | C&I [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans		294
Acquired [Member] | Commercial Credit Exposure [Member] | CRE [Member]
Credit Quality by Loan Class [Abstract]
Net loans		60,937
Acquired [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Pass [Member]
Credit Quality by Loan Class [Abstract]
Net loans		60,545
Acquired [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Special Mention [Member]
Credit Quality by Loan Class [Abstract]
Net loans		0
Acquired [Member] | Commercial Credit Exposure [Member] | CRE [Member] | Substandard [Member]
Credit Quality by Loan Class [Abstract]
Net loans		392
Acquired [Member] | Business Banking Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans		34,965
Acquired [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans		32,030
Acquired [Member] | Business Banking Credit Exposure [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans		2,935
Acquired [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member]
Credit Quality by Loan Class [Abstract]
Net loans		34,965
Acquired [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Non-classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans		32,030
Acquired [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Classified [Member]
Credit Quality by Loan Class [Abstract]
Net loans		2,935
Acquired [Member] | Consumer Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans		23,733
Acquired [Member] | Consumer Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		23,628
Acquired [Member] | Consumer Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		105
Acquired [Member] | Consumer Credit Exposure [Member] | Direct [Member]
Credit Quality by Loan Class [Abstract]
Net loans		23,733
Acquired [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		23,628
Acquired [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		105
Acquired [Member] | Residential Real Estate Credit Exposure [Member]
Credit Quality by Loan Class [Abstract]
Net loans		125,879
Acquired [Member] | Residential Real Estate Credit Exposure [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		124,509
Acquired [Member] | Residential Real Estate Credit Exposure [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		1,370
Acquired [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member]
Credit Quality by Loan Class [Abstract]
Net loans		125,879
Acquired [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member] | Performing [Member]
Credit Quality by Loan Class [Abstract]
Net loans		124,509
Acquired [Member] | Residential Real Estate Credit Exposure [Member] | Residential Real Estate [Member] | Nonperforming [Member]
Credit Quality by Loan Class [Abstract]
Net loans		$ 1,370