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Investment Securities Available for Sale (Schedule of Gross Unrealized Losses on Investment Securities and Fair Value) (Details) - USD ($) $ in Thousands | Jun. 30, 2023 | Dec. 31, 2022
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | $ 1,693,261 | $ 2,523,310
Less than 12 months, gross unrealized losses | (74,755) | (173,930)
12 months or longer, fair value | 7,851,551 | 6,989,855
12 months or longer, gross unrealized losses | (1,478,451) | (1,423,854)
Total, fair value | 9,544,812 | 9,513,165
Total, gross unrealized losses | (1,553,206) | (1,597,784)
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 92,580 | 139,737
Less than 12 months, gross unrealized losses | (4,858) | (6,789)
12 months or longer, fair value | 356,275 | 307,582
12 months or longer, gross unrealized losses | (38,878) | (37,351)
Total, fair value | 448,855 | 447,319
Total, gross unrealized losses | (43,736) | (44,140)
U.S. Government agency securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 258 | 28,938
Less than 12 months, gross unrealized losses | 0 | (1,053)
12 months or longer, fair value | 48,346 | 19,603
12 months or longer, gross unrealized losses | (3,794) | (2,560)
Total, fair value | 48,604 | 48,541
Total, gross unrealized losses | (3,794) | (3,613)
Mortgage-backed securities issued by U.S. Government agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 301,213 | 187,655
Less than 12 months, gross unrealized losses | (5,938) | (5,952)
12 months or longer, fair value | 516,137 | 521,395
12 months or longer, gross unrealized losses | (104,743) | (107,516)
Total, fair value | 817,350 | 709,050
Total, gross unrealized losses | (110,681) | (113,468)
Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 893,627 | 1,473,348
Less than 12 months, gross unrealized losses | (45,280) | (120,135)
12 months or longer, fair value | 5,832,438 | 5,365,233
12 months or longer, gross unrealized losses | (1,156,966) | (1,130,105)
Total, fair value | 6,726,065 | 6,838,581
Total, gross unrealized losses | (1,202,246) | (1,250,240)
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 | 11,090 | 119,649
Less than 12 months, gross unrealized losses | (489) | (10,311)
12 months or longer, fair value | 604,860 | 535,478
12 months or longer, gross unrealized losses | (116,498) | (104,060)
Total, fair value | 615,950 | 655,127
Total, gross unrealized losses | (116,987) | (114,371)
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 | 394,493 | 565,382
Less than 12 months, gross unrealized losses | (18,190) | (29,383)
12 months or longer, fair value | 484,857 | 240,564
12 months or longer, gross unrealized losses | (57,252) | (42,262)
Total, fair value | 879,350 | 805,946
Total, gross unrealized losses | (75,442) | (71,645)
Corporate debt securities and other debt securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 months, fair value | 0 | 8,601
Less than 12 months, gross unrealized losses | 0 | (307)
12 months or longer, fair value | 8,638 | 0
12 months or longer, gross unrealized losses | (320) | 0
Total, fair value | 8,638 | 8,601
Total, gross unrealized losses | $ (320) | $ (307)

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