Loans and Leases and Allowance for Credit Losses - Risk category of loans by class of loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Risk category of loans by class of loans
Total loans	$ 8,812,553	$ 8,383,401
Pass
Risk category of loans by class of loans
Total loans	8,558,459	8,201,872
Watch
Risk category of loans by class of loans
Total loans	93,703	66,969
Substandard
Risk category of loans by class of loans
Total loans	160,391	114,560
Doubtful / Loss
Risk category of loans by class of loans
Total loans	0	0
Loans Receivable
Risk category of loans by class of loans
Total loans, excluding PCI loans	8,753,907	8,308,952
Carrying value of PCI loans	58,646	74,449
Total loans	8,812,553	8,383,401
Loans Receivable | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	8,517,776	8,154,010
Carrying value of PCI loans	40,683	47,862
Loans Receivable | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	83,930	50,556
Carrying value of PCI loans	9,773	16,413
Loans Receivable | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	152,201	104,386
Carrying value of PCI loans	8,190	10,174
Loans Receivable | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Indirect auto
Risk category of loans by class of loans
Total loans, excluding PCI loans		207,692
Carrying value of PCI loans	0	0
Total loans	0	207,692
Loans Receivable | Indirect auto | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans		205,632
Carrying value of PCI loans		0
Loans Receivable | Indirect auto | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans		0
Carrying value of PCI loans		0
Loans Receivable | Indirect auto | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans		2,060
Carrying value of PCI loans		0
Loans Receivable | Indirect auto | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans		0
Carrying value of PCI loans		0
Loans Receivable | Commercial
Risk category of loans by class of loans
Total loans, excluding PCI loans	6,622,646	6,037,023
Carrying value of PCI loans	46,947	62,420
Total loans	6,669,593	6,099,443
Loans Receivable | Commercial | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	6,406,957	5,900,234
Carrying value of PCI loans	30,570	38,276
Loans Receivable | Commercial | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	83,922	50,537
Carrying value of PCI loans	9,773	16,413
Loans Receivable | Commercial | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	131,767	86,252
Carrying value of PCI loans	6,604	7,731
Loans Receivable | Commercial | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Commercial | Owner occupied commercial real estate
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,711,681	1,638,052
Carrying value of PCI loans	8,546	9,852
Total loans	1,720,227	1,647,904
Loans Receivable | Commercial | Owner occupied commercial real estate | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,638,398	1,585,797
Carrying value of PCI loans	3,238	3,352
Loans Receivable | Commercial | Owner occupied commercial real estate | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	24,563	16,651
Carrying value of PCI loans	2,797	2,774
Loans Receivable | Commercial | Owner occupied commercial real estate | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	48,720	35,604
Carrying value of PCI loans	2,511	3,726
Loans Receivable | Commercial | Owner occupied commercial real estate | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Commercial | Income producing commercial real estate
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,980,722	1,774,109
Carrying value of PCI loans	27,228	38,311
Total loans	2,007,950	1,812,420
Loans Receivable | Commercial | Income producing commercial real estate | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,914,524	1,735,456
Carrying value of PCI loans	19,648	23,430
Loans Receivable | Commercial | Income producing commercial real estate | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	40,676	20,923
Carrying value of PCI loans	6,305	13,403
Loans Receivable | Commercial | Income producing commercial real estate | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	25,522	17,730
Carrying value of PCI loans	1,275	1,478
Loans Receivable | Commercial | Income producing commercial real estate | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Commercial | Commercial & industrial
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,220,331	1,277,939
Carrying value of PCI loans	326	408
Total loans	1,220,657	1,278,347
Loans Receivable | Commercial | Commercial & industrial | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,156,366	1,247,206
Carrying value of PCI loans	104	266
Loans Receivable | Commercial | Commercial & industrial | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	16,385	8,430
Carrying value of PCI loans	81	48
Loans Receivable | Commercial | Commercial & industrial | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	47,580	22,303
Carrying value of PCI loans	141	94
Loans Receivable | Commercial | Commercial & industrial | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Commercial | Construction
Risk category of loans by class of loans
Total loans, excluding PCI loans	969,353	790,251
Carrying value of PCI loans	6,862	5,907
Total loans	976,215	796,158
Loans Receivable | Commercial | Construction | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	960,251	777,780
Carrying value of PCI loans	3,628	3,503
Loans Receivable | Commercial | Construction | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	2,298	4,533
Carrying value of PCI loans	590	188
Loans Receivable | Commercial | Construction | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	6,804	7,938
Carrying value of PCI loans	2,644	2,216
Loans Receivable | Commercial | Construction | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Commercial | Equipment financing
Risk category of loans by class of loans
Total loans, excluding PCI loans	740,559	556,672
Carrying value of PCI loans	3,985	7,942
Total loans	744,544	564,614
Loans Receivable | Commercial | Equipment financing | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	737,418	553,995
Carrying value of PCI loans	3,952	7,725
Loans Receivable | Commercial | Equipment financing | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Commercial | Equipment financing | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	3,141	2,677
Carrying value of PCI loans	33	217
Loans Receivable | Commercial | Equipment financing | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Residential | Construction
Risk category of loans by class of loans
Total loans, excluding PCI loans	236,063	210,277
Carrying value of PCI loans	374	734
Total loans	236,437	211,011
Loans Receivable | Residential | Construction | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	234,791	209,744
Carrying value of PCI loans	348	687
Loans Receivable | Residential | Construction | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Residential | Construction | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,272	533
Carrying value of PCI loans	26	47
Loans Receivable | Residential | Construction | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Residential | Residential mortgage
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,108,037	1,040,082
Carrying value of PCI loans	9,579	9,150
Total loans	1,117,616	1,049,232
Loans Receivable | Residential | Residential mortgage | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,093,902	1,028,660
Carrying value of PCI loans	8,112	6,914
Loans Receivable | Residential | Residential mortgage | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Residential | Residential mortgage | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	14,135	11,422
Carrying value of PCI loans	1,467	2,236
Loans Receivable | Residential | Residential mortgage | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Residential | Home equity lines of credit
Risk category of loans by class of loans
Total loans, excluding PCI loans	659,265	692,398
Carrying value of PCI loans	1,410	1,612
Total loans	660,675	694,010
Loans Receivable | Residential | Home equity lines of credit | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	654,619	688,493
Carrying value of PCI loans	1,350	1,492
Loans Receivable | Residential | Home equity lines of credit | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Residential | Home equity lines of credit | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	4,646	3,905
Carrying value of PCI loans	60	120
Loans Receivable | Residential | Home equity lines of credit | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	0	0
Loans Receivable | Consumer
Risk category of loans by class of loans
Total loans, excluding PCI loans	127,896	121,480
Carrying value of PCI loans	336	533
Total loans	128,232	122,013
Loans Receivable | Consumer | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	127,507	121,247
Carrying value of PCI loans	303	493
Loans Receivable | Consumer | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	8	19
Carrying value of PCI loans	0	0
Loans Receivable | Consumer | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	381	214
Carrying value of PCI loans	33	40
Loans Receivable | Consumer | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	$ 0	$ 0