Fair Value Measurements - General Disclosures (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	$ 2,261,187	$ 1,648,257
Equity securities	5,530	5,952
Loans held for sale, at fair value	42,813	68,699
U.S. Treasury securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	27,837	51,737
Obligations of U.S. government corporations and agencies
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	69,519	163,000
Obligations of states and political subdivisions
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	304,711	268,291
Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	418,616	139,287
Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	1,368,315	921,966
Corporate debt securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	72,189	103,976
Recurring basis
Financial assets and financial liabilities measured at fair value
Equity securities	5,530	5,952
Loans held for sale, at fair value	42,813	68,699
Recurring basis \| Derivative assets
Financial assets and financial liabilities measured at fair value
Derivative asset	33,918	13,400
Recurring basis \| Derivative liabilities
Financial assets and financial liabilities measured at fair value
Derivative liability	38,403	14,821
Recurring basis \| U.S. Treasury securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	27,837	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	69,519	163,000
Recurring basis \| Obligations of states and political subdivisions
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	304,711	268,291
Recurring basis \| Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	418,616	139,287
Recurring basis \| Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	1,368,315	921,966
Recurring basis \| Corporate debt securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	72,189	103,976
Recurring basis \| Level 2
Financial assets and financial liabilities measured at fair value
Equity securities	5,530	5,952
Loans held for sale, at fair value	42,813	68,699
Recurring basis \| Level 2 \| Derivative assets
Financial assets and financial liabilities measured at fair value
Derivative asset	33,918	13,400
Recurring basis \| Level 2 \| Derivative liabilities
Financial assets and financial liabilities measured at fair value
Derivative liability	38,403	14,821
Recurring basis \| Level 2 \| U.S. Treasury securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	27,837	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	69,519	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	304,711	268,291
Recurring basis \| Level 2 \| Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	418,616	139,287
Recurring basis \| Level 2 \| Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	1,368,315	921,966
Recurring basis \| Level 2 \| Corporate debt securities
Financial assets and financial liabilities measured at fair value
Debt securities available for sale	$ 72,189	$ 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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