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Fair Value Accounting (Schedule of Financial Instruments Measured at Fair Value on Recurring Basis) (Details) - USD ($) $ in Thousands | Sep. 30, 2023 | Dec. 31, 2022
--- | --- | ---
Assets |  |
Investment securities available for sale | $ 9,237,191 | $ 9,678,103
Mortgage loans held for sale | 48,994 | 51,136
Collateralized mortgage obligations issued by U.S. Government sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 578,836 | 655,127
U.S. Treasury securities |  |
Assets |  |
Investment securities available for sale | 509,460 | 471,813
Mortgage-backed securities issued by U.S. Government agencies |  |
Assets |  |
Investment securities available for sale | 892,254 | 792,749
Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 6,261,752 | 6,895,070
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 938,735 | 805,945
Corporate debt securities and other debt securities |  |
Assets |  |
Investment securities available for sale | 8,648 | 8,601
Level 1 |  |
Assets |  |
Trading securities | 0 | 0
Investment securities available for sale | 509,460 | 471,813
Other investments | 0 | 0
Mutual funds and mutual funds held in rabbi trusts | 49,119 | 42,659
Derivative assets | 0 | 0
Liabilities |  |
Securities sold short | 2,362 | 3,370
Mutual funds held in rabbi trusts | 34,768 | 27,944
Derivative liabilities | 0 | 0
Level 2 |  |
Assets |  |
Trading securities | 13,555 | 8,295
Investment securities available for sale | 8,727,731 | 9,206,290
Other investments | 0 | 0
Mutual funds and mutual funds held in rabbi trusts | 0 | 0
Derivative assets | 161,163 | 89,815
Liabilities |  |
Securities sold short | 0 | 0
Mutual funds held in rabbi trusts | 0 | 0
Derivative liabilities | 387,118 | 339,227
Level 3 |  |
Assets |  |
Trading securities | 0 | 0
Investment securities available for sale | 0 | 0
Other investments | 11,789 | 11,172
Mutual funds and mutual funds held in rabbi trusts | 0 | 0
Derivative assets | 0 | 0
Liabilities |  |
Securities sold short | 0 | 0
Mutual funds held in rabbi trusts | 0 | 0
Derivative liabilities | 0 | 0
Fair Value, Measurements, Recurring Basis |  |
Assets |  |
Trading securities | 13,555 | 8,295
Investment securities available for sale | 9,237,191 | 9,678,103
Mortgage loans held for sale | 48,994 | 51,136
Other investments | 11,789 | 11,172
Mutual funds and mutual funds held in rabbi trusts | 49,119 | 42,659
Derivative assets | 161,163 | 89,815
Liabilities |  |
Securities sold short | 2,362 | 3,370
Mutual funds held in rabbi trusts | 34,768 | 27,944
Derivative liabilities | 387,118 | 339,227
Fair Value, Measurements, Recurring Basis | Collateralized mortgage obligations issued by U.S. Government sponsored enterprises |  |
Assets |  |
Trading securities | 2,702 | 2,991
Investment securities available for sale | 578,836 | 655,127
Fair Value, Measurements, Recurring Basis | Other mortgage-backed securities |  |
Assets |  |
Trading securities | 2,379 | 3,185
Fair Value, Measurements, Recurring Basis | State and municipal securities |  |
Assets |  |
Trading securities | 0 | 48
Fair Value, Measurements, Recurring Basis | Asset-backed securities |  |
Assets |  |
Trading securities | 8,399 | 2,071
Fair Value, Measurements, Recurring Basis | Other Investments |  |
Assets |  |
Trading securities | 75 | 0
Fair Value, Measurements, Recurring Basis | U.S. Treasury securities |  |
Assets |  |
Investment securities available for sale | 509,460 | 471,813
Fair Value, Measurements, Recurring Basis | U.S. Government agency securities |  |
Assets |  |
Investment securities available for sale | 47,506 | 48,798
Fair Value, Measurements, Recurring Basis | Mortgage-backed securities issued by U.S. Government agencies |  |
Assets |  |
Investment securities available for sale | 892,254 | 792,749
Fair Value, Measurements, Recurring Basis | Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 6,261,752 | 6,895,070
Fair Value, Measurements, Recurring Basis | Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 938,735 | 805,945
Fair Value, Measurements, Recurring Basis | Corporate debt securities and other debt securities |  |
Assets |  |
Investment securities available for sale | 8,648 | 8,601
Fair Value, Measurements, Recurring Basis | Level 1 |  |
Assets |  |
Trading securities | 0 | 0
Investment securities available for sale | 509,460 | 471,813
Mortgage loans held for sale | 0 | 0
Other investments | 0 | 0
Mutual funds and mutual funds held in rabbi trusts | 49,119 | 42,659
Derivative assets | 0 | 0
Liabilities |  |
Securities sold short | 2,362 | 3,370
Mutual funds held in rabbi trusts | 34,768 | 27,944
Derivative liabilities | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 1 | Collateralized mortgage obligations issued by U.S. Government sponsored enterprises |  |
Assets |  |
Trading securities | 0 | 0
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 1 | Other mortgage-backed securities |  |
Assets |  |
Trading securities | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 1 | State and municipal securities |  |
Assets |  |
Trading securities | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 1 | Asset-backed securities |  |
Assets |  |
Trading securities | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 1 | Other Investments |  |
Assets |  |
Trading securities | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 1 | U.S. Treasury securities |  |
Assets |  |
Investment securities available for sale | 509,460 | 471,813
Fair Value, Measurements, Recurring Basis | Level 1 | U.S. Government agency securities |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 1 | Mortgage-backed securities issued by U.S. Government agencies |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 1 | Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 1 | Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 1 | Corporate debt securities and other debt securities |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 2 |  |
Assets |  |
Trading securities | 13,555 | 8,295
Investment securities available for sale | 8,727,731 | 9,206,290
Mortgage loans held for sale | 48,994 | 51,136
Other investments | 0 | 0
Mutual funds and mutual funds held in rabbi trusts | 0 | 0
Derivative assets | 161,163 | 89,815
Liabilities |  |
Securities sold short | 0 | 0
Mutual funds held in rabbi trusts | 0 | 0
Derivative liabilities | 387,118 | 339,227
Fair Value, Measurements, Recurring Basis | Level 2 | Collateralized mortgage obligations issued by U.S. Government sponsored enterprises |  |
Assets |  |
Trading securities | 2,702 | 2,991
Investment securities available for sale | 578,836 | 655,127
Fair Value, Measurements, Recurring Basis | Level 2 | Other mortgage-backed securities |  |
Assets |  |
Trading securities | 2,379 | 3,185
Fair Value, Measurements, Recurring Basis | Level 2 | State and municipal securities |  |
Assets |  |
Trading securities | 0 | 48
Fair Value, Measurements, Recurring Basis | Level 2 | Asset-backed securities |  |
Assets |  |
Trading securities | 8,399 | 2,071
Fair Value, Measurements, Recurring Basis | Level 2 | Other Investments |  |
Assets |  |
Trading securities | 75 | 0
Fair Value, Measurements, Recurring Basis | Level 2 | U.S. Treasury securities |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 2 | U.S. Government agency securities |  |
Assets |  |
Investment securities available for sale | 47,506 | 48,798
Fair Value, Measurements, Recurring Basis | Level 2 | Mortgage-backed securities issued by U.S. Government agencies |  |
Assets |  |
Investment securities available for sale | 892,254 | 792,749
Fair Value, Measurements, Recurring Basis | Level 2 | Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 6,261,752 | 6,895,070
Fair Value, Measurements, Recurring Basis | Level 2 | Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 938,735 | 805,945
Fair Value, Measurements, Recurring Basis | Level 2 | Corporate debt securities and other debt securities |  |
Assets |  |
Investment securities available for sale | 8,648 | 8,601
Fair Value, Measurements, Recurring Basis | Level 3 |  |
Assets |  |
Trading securities | 0 | 0
Investment securities available for sale | 0 | 0
Mortgage loans held for sale | 0 | 0
Other investments | 11,789 | 11,172
Mutual funds and mutual funds held in rabbi trusts | 0 | 0
Derivative assets | 0 | 0
Liabilities |  |
Securities sold short | 0 | 0
Mutual funds held in rabbi trusts | 0 | 0
Derivative liabilities | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | Collateralized mortgage obligations issued by U.S. Government sponsored enterprises |  |
Assets |  |
Trading securities | 0 | 0
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | Other mortgage-backed securities |  |
Assets |  |
Trading securities | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | State and municipal securities |  |
Assets |  |
Trading securities | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | Asset-backed securities |  |
Assets |  |
Trading securities | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | Other Investments |  |
Assets |  |
Trading securities | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | U.S. Treasury securities |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | U.S. Government agency securities |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | Mortgage-backed securities issued by U.S. Government agencies |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises |  |
Assets |  |
Investment securities available for sale | 0 | 0
Fair Value, Measurements, Recurring Basis | Level 3 | Corporate debt securities and other debt securities |  |
Assets |  |
Investment securities available for sale | $ 0 | $ 0

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