Fair Value Measurements - General Disclosures (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	$ 2,080,849	$ 1,648,257
Equity securities	17,808	5,952
Loans held for sale, at fair value	87,772	68,699
U.S. Treasury securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	29,937	51,737
Obligations of U.S. government corporations and agencies
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	78,478	163,000
Obligations of states and political subdivisions
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	316,120	268,291
Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	357,243	139,287
Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	1,218,526	921,966
Corporate debt securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	80,545	103,976
Recurring basis
Financial assets and financial liabilities measured at fair value
Equity securities	17,808	5,952
Loans held for sale, at fair value	87,772	68,699
Recurring basis \| Derivative assets
Financial assets and financial liabilities measured at fair value
Derivative asset	39,711	13,400
Recurring basis \| Derivative liabilities
Financial assets and financial liabilities measured at fair value
Derivative liability	45,525	14,821
Recurring basis \| U.S. Treasury securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	29,937	51,737
Recurring basis \| Obligations of U.S. government corporations and agencies
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	78,478	163,000
Recurring basis \| Obligations of states and political subdivisions
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	316,120	268,291
Recurring basis \| Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	357,243	139,287
Recurring basis \| Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	1,218,526	921,966
Recurring basis \| Corporate debt securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	80,545	103,976
Recurring basis \| Level 1
Financial assets and financial liabilities measured at fair value
Equity securities	13,119
Recurring basis \| Level 2
Financial assets and financial liabilities measured at fair value
Equity securities	4,689	5,952
Loans held for sale, at fair value	87,772	68,699
Recurring basis \| Level 2 \| Derivative assets
Financial assets and financial liabilities measured at fair value
Derivative asset	39,711	13,400
Recurring basis \| Level 2 \| Derivative liabilities
Financial assets and financial liabilities measured at fair value
Derivative liability	45,525	14,821
Recurring basis \| Level 2 \| U.S. Treasury securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	29,937	51,737
Recurring basis \| Level 2 \| Obligations of U.S. government corporations and agencies
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	78,478	163,000
Recurring basis \| Level 2 \| Obligations of states and political subdivisions
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	316,120	268,291
Recurring basis \| Level 2 \| Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	357,243	139,287
Recurring basis \| Level 2 \| Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	1,218,526	921,966
Recurring basis \| Level 2 \| Corporate debt securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	$ 80,545	$ 103,976

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

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