Loans and Leases and Allowance for Credit Losses - Major classifications of loans and lease portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Classifications of loans
Total loans	$ 8,383,401	$ 7,735,572
Less allowance for loan losses	(61,203)	(58,914)
Loans, net	8,322,198	7,676,658
Loans Receivable
Classifications of loans
Total loans	8,383,401	7,735,572
Less allowance for loan losses	(61,203)	(58,914)
Loans, net	8,322,198	7,676,658
Loans Receivable \| Home equity lines of credit
Classifications of loans
Total loans	694,010	731,227
Loans Receivable \| Indirect auto
Classifications of loans
Total loans	207,692	358,185
Loans Receivable \| Commercial
Classifications of loans
Total loans	6,099,443	5,362,093
Loans Receivable \| Commercial \| Owner occupied commercial real estate
Classifications of loans
Total loans	1,647,904	1,923,993
Loans Receivable \| Commercial \| Income producing commercial real estate
Classifications of loans
Total loans	1,812,420	1,595,174
Loans Receivable \| Commercial \| Construction
Classifications of loans
Total loans	796,158	711,936
Loans Receivable \| Commercial \| Equipment financing
Classifications of loans
Total loans	564,614	0
Loans Receivable \| Commercial \| Commercial & industrial
Classifications of loans
Total loans	1,278,347	1,130,990
Loans Receivable \| Residential \| Residential mortgage
Classifications of loans
Total loans	1,049,232	973,544
Loans Receivable \| Residential \| Construction
Classifications of loans
Total loans	211,011	183,019
Loans Receivable \| Consumer direct
Classifications of loans
Total loans	$ 122,013	$ 127,504

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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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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