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Debt Securities - Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Investment Securities (Details) - USD ($) $ in Thousands | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Available-for-sale |  |
Amortized Cost | $ 9,175,423 | $ 5,145,866
Gross Unrealized Gains | 68,117 | 192,740
Gross Unrealized Losses | (72,691) | (792)
Fair Value | 9,170,849 | 5,337,814
Held-to-maturity |  |
Amortized Cost | 1,199,164 | 189,836
Gross Unrealized Gains | 22,878 | 13,380
Gross Unrealized Losses | (1,159) | 0
Fair Value | 1,220,883 | 203,216
Total debt securities |  |
Amortized Cost | 10,374,587 | 5,335,702
Gross Unrealized Gains | 90,995 | 206,120
Gross Unrealized Losses | (73,850) | (792)
Fair Value | 10,391,732 | 5,541,030
U.S. government and federal agency |  |
Available-for-sale |  |
Amortized Cost | 1,356,171 | 38,568
Gross Unrealized Gains | 174 | 287
Gross Unrealized Losses | (9,596) | (267)
Fair Value | 1,346,749 | 38,588
U.S. government sponsored enterprises |  |
Available-for-sale |  |
Amortized Cost | 241,687 | 9,747
Gross Unrealized Gains | 2 | 34
Gross Unrealized Losses | (996) | 0
Fair Value | 240,693 | 9,781
State and local governments |  |
Available-for-sale |  |
Amortized Cost | 461,414 | 1,321,763
Gross Unrealized Gains | 27,567 | 94,974
Gross Unrealized Losses | (123) | (54)
Fair Value | 488,858 | 1,416,683
Held-to-maturity |  |
Amortized Cost | 1,199,164 | 189,836
Gross Unrealized Gains | 22,878 | 13,380
Gross Unrealized Losses | (1,159) | 0
Fair Value | 1,220,883 | 203,216
Corporate bonds |  |
Available-for-sale |  |
Amortized Cost | 175,697 | 336,867
Gross Unrealized Gains | 5,072 | 12,239
Gross Unrealized Losses | (17) | (8)
Fair Value | 180,752 | 349,098
Residential mortgage-backed securities |  |
Available-for-sale |  |
Amortized Cost | 5,744,505 | 2,261,463
Gross Unrealized Gains | 9,420 | 27,631
Gross Unrealized Losses | (54,266) | (4)
Fair Value | 5,699,659 | 2,289,090
Commercial mortgage-backed securities |  |
Available-for-sale |  |
Amortized Cost | 1,195,949 | 1,177,458
Gross Unrealized Gains | 25,882 | 57,575
Gross Unrealized Losses | (7,693) | (459)
Fair Value | $ 1,214,138 | $ 1,234,574

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- Definition This item represents the cost of available-for-sale and held-to-maturity debt securities, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details
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- Definition Fair value of investments in debt securities classified as available-for sale and held-to-maturity. + References No definition available. + Details
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- Definition Amount of accumulated unrealized gain before deducting unrealized loss on investments in available-for-sale and held-to-maturity securities impacting investments. + References No definition available. + Details
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- Definition Amount of accumulated unrealized loss before deducting unrealized gain on investments in available-for-sale and held-to-maturity securities impacting investments. + References No definition available. + Details
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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
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- Definition Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
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- Definition Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27232-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123581744&loc=SL120269820-111563 + Details
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