Loans and Leases and Allowance for Credit Losses - Aging of recorded investment in loans, including accruing and nonaccrual loans (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Loans by aging category
PCI Loans		$ 58,646
Total loans	$ 11,798,910	8,812,553
Commercial | Owner occupied commercial real estate
Loans by aging category
Total loans	2,008,674
Commercial | Income producing commercial real estate
Loans by aging category
Total loans	2,493,625
Commercial | Commercial & industrial
Loans by aging category
Total loans	3,104,868
Commercial | Construction
Loans by aging category
Total loans	981,371
Commercial | Equipment financing
Loans by aging category
Total loans	823,022
Residential | Construction
Loans by aging category
Total loans	263,266
Residential | Residential mortgage
Loans by aging category
Total loans	1,269,548
Residential | Home equity lines of credit
Loans by aging category
Total loans	706,877
Consumer
Loans by aging category
Total loans	147,659
Loans receivable
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		41,240
Current Loans	11,737,229	8,712,667
PCI Loans		58,646
Total loans	11,798,910	8,812,553
Loans receivable | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		17,892
Loans receivable | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		7,623
Loans receivable | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		15,725
Loans receivable | Commercial
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		25,971
Current Loans	9,372,656	6,596,675
PCI Loans		46,947
Total loans	9,411,560	6,669,593
Loans receivable | Commercial | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		9,547
Loans receivable | Commercial | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		4,684
Loans receivable | Commercial | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		11,740
Loans receivable | Commercial | Owner occupied commercial real estate
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		10,999
Current Loans	1,996,903	1,700,682
PCI Loans		8,546
Total loans	2,008,674	1,720,227
Loans receivable | Commercial | Owner occupied commercial real estate | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		2,913
Loans receivable | Commercial | Owner occupied commercial real estate | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		2,007
Loans receivable | Commercial | Owner occupied commercial real estate | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		6,079
Loans receivable | Commercial | Income producing commercial real estate
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		1,669
Current Loans	2,479,614	1,979,053
PCI Loans		27,228
Total loans	2,493,625	2,007,950
Loans receivable | Commercial | Income producing commercial real estate | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		562
Loans receivable | Commercial | Income producing commercial real estate | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		706
Loans receivable | Commercial | Income producing commercial real estate | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		401
Loans receivable | Commercial | Commercial & industrial
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		4,750
Current Loans	3,099,387	1,215,581
PCI Loans		326
Total loans	3,104,868	1,220,657
Loans receivable | Commercial | Commercial & industrial | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		2,140
Loans receivable | Commercial | Commercial & industrial | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		491
Loans receivable | Commercial | Commercial & industrial | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		2,119
Loans receivable | Commercial | Construction
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		2,520
Current Loans	979,169	966,833
PCI Loans		6,862
Total loans	981,371	976,215
Loans receivable | Commercial | Construction | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		1,867
Loans receivable | Commercial | Construction | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		557
Loans receivable | Commercial | Construction | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		96
Loans receivable | Commercial | Equipment financing
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		6,033
Current Loans	817,583	734,526
PCI Loans		3,985
Total loans	823,022	744,544
Loans receivable | Commercial | Equipment financing | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		2,065
Loans receivable | Commercial | Equipment financing | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		923
Loans receivable | Commercial | Equipment financing | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		3,045
Loans receivable | Residential | Construction
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		852
Current Loans	262,002	235,211
PCI Loans		374
Total loans	263,266	236,437
Loans receivable | Residential | Construction | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		325
Loans receivable | Residential | Construction | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		125
Loans receivable | Residential | Construction | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		402
Loans receivable | Residential | Residential mortgage
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		10,038
Current Loans	1,252,937	1,097,999
PCI Loans		9,579
Total loans	1,269,548	1,117,616
Loans receivable | Residential | Residential mortgage | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		5,655
Loans receivable | Residential | Residential mortgage | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		2,212
Loans receivable | Residential | Residential mortgage | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		2,171
Loans receivable | Residential | Home equity lines of credit
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		3,503
Current Loans	702,457	655,762
PCI Loans		1,410
Total loans	706,877	660,675
Loans receivable | Residential | Home equity lines of credit | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		1,697
Loans receivable | Residential | Home equity lines of credit | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		421
Loans receivable | Residential | Home equity lines of credit | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		1,385
Loans receivable | Consumer
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		876
Current Loans	147,177	127,020
PCI Loans		336
Total loans	$ 147,659	128,232
Loans receivable | Consumer | Loans Past Due, 30 - 59 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		668
Loans receivable | Consumer | Loans Past Due, 60 - 89 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		181
Loans receivable | Consumer | Loans Past Due, over 90 Days
Loans by aging category
Loans Past Due - Accruing and Nonaccrual		$ 27