Loans and Leases and Allowance for Credit Losses - Risk category of loans by class of loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Risk category of loans by class of loans
Total loans	$ 8,383,401	$ 7,735,572
Pass
Risk category of loans by class of loans
Total loans	8,201,872	7,475,802
Watch
Risk category of loans by class of loans
Total loans	66,969	118,951
Substandard
Risk category of loans by class of loans
Total loans	114,560	140,819
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	8,308,952	7,637,058
Carrying value of PCI loans	74,449	98,514
Total loans	8,383,401	7,735,572
Loans Receivable | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	8,154,010	7,443,117
Carrying value of PCI loans	47,862	32,685
Loans Receivable | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	50,556	85,350
Carrying value of PCI loans	16,413	33,601
Loans Receivable | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	104,386	108,591
Carrying value of PCI loans	10,174	32,228
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 | Home equity lines of credit
Risk category of loans by class of loans
Total loans, excluding PCI loans	692,398	728,336
Carrying value of PCI loans	1,612	2,891
Total loans	694,010	731,227
Loans Receivable | Home equity lines of credit | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	688,493	721,142
Carrying value of PCI loans	1,492	1,579
Loans Receivable | 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	427
Loans Receivable | Home equity lines of credit | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	3,905	7,194
Carrying value of PCI loans	120	885
Loans Receivable | 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 | Indirect auto
Risk category of loans by class of loans
Total loans, excluding PCI loans	207,692	358,185
Carrying value of PCI loans	0	0
Total loans	207,692	358,185
Loans Receivable | Indirect auto | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	205,632	354,788
Carrying value of PCI loans	0	0
Loans Receivable | Indirect auto | 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 | Indirect auto | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	2,060	3,397
Carrying value of PCI loans	0	0
Loans Receivable | Indirect auto | 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
Risk category of loans by class of loans
Total loans, excluding PCI loans	6,037,023	5,281,195
Carrying value of PCI loans	62,420	80,898
Total loans	6,099,443	5,362,093
Loans Receivable | Commercial | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	5,900,234	5,121,054
Carrying value of PCI loans	38,276	20,041
Loans Receivable | Commercial | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	50,537	85,350
Carrying value of PCI loans	16,413	32,991
Loans Receivable | Commercial | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	86,252	74,791
Carrying value of PCI loans	7,731	27,866
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	1,638,052	1,898,234
Carrying value of PCI loans	9,852	25,759
Total loans	1,647,904	1,923,993
Loans Receivable | Commercial | Owner occupied commercial real estate | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,585,797	1,833,469
Carrying value of PCI loans	3,352	2,400
Loans Receivable | Commercial | Owner occupied commercial real estate | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	16,651	33,571
Carrying value of PCI loans	2,774	8,163
Loans Receivable | Commercial | Owner occupied commercial real estate | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	35,604	31,194
Carrying value of PCI loans	3,726	15,196
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	1,774,109	1,550,334
Carrying value of PCI loans	38,311	44,840
Total loans	1,812,420	1,595,174
Loans Receivable | Commercial | Income producing commercial real estate | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,735,456	1,495,805
Carrying value of PCI loans	23,430	13,392
Loans Receivable | Commercial | Income producing commercial real estate | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	20,923	30,780
Carrying value of PCI loans	13,403	21,928
Loans Receivable | Commercial | Income producing commercial real estate | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	17,730	23,749
Carrying value of PCI loans	1,478	9,520
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 | Construction
Risk category of loans by class of loans
Total loans, excluding PCI loans	790,251	703,079
Carrying value of PCI loans	5,907	8,857
Total loans	796,158	711,936
Loans Receivable | Commercial | Construction | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	777,780	693,873
Carrying value of PCI loans	3,503	3,866
Loans Receivable | Commercial | Construction | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	4,533	2,947
Carrying value of PCI loans	188	2,228
Loans Receivable | Commercial | Construction | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	7,938	6,259
Carrying value of PCI loans	2,216	2,763
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	556,672	0
Carrying value of PCI loans	7,942	0
Total loans	564,614	0
Loans Receivable | Commercial | Equipment financing | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	553,995	0
Carrying value of PCI loans	7,725	0
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	2,677	0
Carrying value of PCI loans	217	0
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 | Commercial | Commercial & industrial
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,277,939	1,129,548
Carrying value of PCI loans	408	1,442
Total loans	1,278,347	1,130,990
Loans Receivable | Commercial | Commercial & industrial | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,247,206	1,097,907
Carrying value of PCI loans	266	383
Loans Receivable | Commercial | Commercial & industrial | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	8,430	18,052
Carrying value of PCI loans	48	672
Loans Receivable | Commercial | Commercial & industrial | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	22,303	13,589
Carrying value of PCI loans	94	387
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 | Residential | Construction
Risk category of loans by class of loans
Total loans, excluding PCI loans	210,277	182,555
Carrying value of PCI loans	734	464
Total loans	211,011	183,019
Loans Receivable | Residential | Construction | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	209,744	180,567
Carrying value of PCI loans	687	423
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	533	1,988
Carrying value of PCI loans	47	41
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	1,040,082	960,403
Carrying value of PCI loans	9,150	13,141
Total loans	1,049,232	973,544
Loans Receivable | Residential | Residential mortgage | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	1,028,660	939,706
Carrying value of PCI loans	6,914	9,566
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	173
Loans Receivable | Residential | Residential mortgage | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	11,422	20,697
Carrying value of PCI loans	2,236	3,402
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 | Consumer direct
Risk category of loans by class of loans
Total loans, excluding PCI loans	121,480	126,384
Carrying value of PCI loans	533	1,120
Total loans	122,013	127,504
Loans Receivable | Consumer direct | Pass
Risk category of loans by class of loans
Total loans, excluding PCI loans	121,247	125,860
Carrying value of PCI loans	493	1,076
Loans Receivable | Consumer direct | Watch
Risk category of loans by class of loans
Total loans, excluding PCI loans	19	0
Carrying value of PCI loans	0	10
Loans Receivable | Consumer direct | Substandard
Risk category of loans by class of loans
Total loans, excluding PCI loans	214	524
Carrying value of PCI loans	40	34
Loans Receivable | Consumer direct | Doubtful / Loss
Risk category of loans by class of loans
Total loans, excluding PCI loans	0	0
Carrying value of PCI loans	$ 0	$ 0