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Investment Securities Available for Sale (Schedule of Gross Unrealized Losses on Investment Securities and Fair Value) (Details) - USD ($) $ in Thousands | Mar. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | $ 6,482,952 | $ 6,596,065
Less than 12 months, gross unrealized losses | (428,286) | (96,227)
12 months or longer, fair value | 2,963,676 | 1,523,383
12 months or longer, gross unrealized losses | (273,418) | (43,377)
Total, fair value | 9,446,628 | 8,119,448
Total, gross unrealized losses | (701,704) | (139,604)
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 328,920 | 49,648
Less than 12 months, gross unrealized losses | (14,282) | (379)
12 months or longer, fair value | 44,313 | 47,590
12 months or longer, gross unrealized losses | (5,529) | (2,248)
Total, fair value | 373,233 | 97,238
Total, gross unrealized losses | (19,811) | (2,627)
U.S. Government agency securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 20,691 | 21,760
Less than 12 months, gross unrealized losses | (1,471) | (387)
12 months or longer, fair value | 0 | 0
12 months or longer, gross unrealized losses | 0 | 0
Total, fair value | 20,691 | 21,760
Total, gross unrealized losses | (1,471) | (387)
Mortgage-backed securities issued by U.S. Government agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 316,662 | 461,078
Less than 12 months, gross unrealized losses | (19,328) | (5,858)
12 months or longer, fair value | 365,096 | 244,264
12 months or longer, gross unrealized losses | (27,277) | (5,606)
Total, fair value | 681,758 | 705,342
Total, gross unrealized losses | (46,605) | (11,464)
Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 5,225,550 | 5,729,476
Less than 12 months, gross unrealized losses | (365,535) | (82,671)
12 months or longer, fair value | 1,966,572 | 643,758
12 months or longer, gross unrealized losses | (188,380) | (19,409)
Total, fair value | 7,192,122 | 6,373,234
Total, gross unrealized losses | (553,915) | (102,080)
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 366,174 | 187,431
Less than 12 months, gross unrealized losses | (18,823) | (3,981)
12 months or longer, fair value | 441,167 | 504,238
12 months or longer, gross unrealized losses | (35,987) | (12,745)
Total, fair value | 807,341 | 691,669
Total, gross unrealized losses | (54,810) | (16,726)
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 224,955 | 146,672
Less than 12 months, gross unrealized losses | (8,847) | (2,951)
12 months or longer, fair value | 146,528 | 83,533
12 months or longer, gross unrealized losses | (16,245) | (3,369)
Total, fair value | 371,483 | 230,205
Total, gross unrealized losses | $ (25,092) | $ (6,320)

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