Loans and Leases and Allowance for Credit Losses - Major classifications of loans and lease portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Classifications of loans
Total loans	$ 8,812,553	$ 8,383,401
Less allowance for loan losses	(62,089)	(61,203)
Loans, net	8,750,464	8,322,198
Loans Receivable
Classifications of loans
Total loans	8,812,553	8,383,401
Less allowance for loan losses	(62,089)
Loans Receivable \| Indirect auto
Classifications of loans
Total loans	0	207,692
Loans Receivable \| Commercial
Classifications of loans
Total loans	6,669,593	6,099,443
Loans Receivable \| Commercial \| Owner occupied commercial real estate
Classifications of loans
Total loans	1,720,227	1,647,904
Loans Receivable \| Commercial \| Income producing commercial real estate
Classifications of loans
Total loans	2,007,950	1,812,420
Loans Receivable \| Commercial \| Commercial & industrial
Classifications of loans
Total loans	1,220,657	1,278,347
Loans Receivable \| Commercial \| Construction
Classifications of loans
Total loans	976,215	796,158
Loans Receivable \| Commercial \| Equipment financing
Classifications of loans
Total loans	744,544	564,614
Loans Receivable \| Residential \| Residential mortgage
Classifications of loans
Total loans	1,117,616	1,049,232
Loans Receivable \| Residential \| Home equity lines of credit
Classifications of loans
Total loans	660,675	694,010
Loans Receivable \| Residential \| Construction
Classifications of loans
Total loans	236,437	211,011
Loans Receivable \| Consumer
Classifications of loans
Total loans	$ 128,232	$ 122,013

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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