Loans - Loan Portfolio (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 12,519,604	$ 11,446,783
Deferred loan fees included in total loans	7,382	6,715
Overdrawn demand deposits included in total loans	8,875	8,583
Commercial and industrial \| Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,524,401	4,120,293
Commercial and industrial \| Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	430,589	430,928
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,826,012	4,596,249
Commercial real estate \| Office, retail, and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,936,577	1,820,917
Commercial real estate \| Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	787,155	764,185
Commercial real estate \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	654,607	649,337
Commercial real estate \| Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,447,673	1,361,810
Total corporate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	9,781,002	9,147,470
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,738,602	2,299,313
Consumer loans \| Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	874,686	851,607
Consumer loans \| 1-4 family mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,391,814	1,017,181
Consumer loans \| Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 472,102	$ 430,525

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Carrying value as of the balance sheet date of payments made in excess of existing cash balances, which will be honored by the bank but reflected as a loan to the entity. Overdrafts generally have a very short time frame for correction or repayment and are therefore more similar to short-term bank financing than trade financing.

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Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

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

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