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Investments - Gross Unrealized Losses and Fair Value for Mortgage-Backed in Unrealized Loss Position (Details) - USD ($) $ in Thousands | Mar. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Less than 12 months |  |
Gross Unrealized Losses | $ (77,395) | $ (18,989)
Estimated Fair Value | 1,978,196 | 1,593,655
12 months or more |  |
Gross Unrealized Losses | (21,332) | (1,540)
Estimated Fair Value | 276,587 | 36,587
Total |  |
Gross Unrealized Losses | (98,727) | (20,529)
Estimated Fair Value | 2,254,783 | 1,630,242
Mortgage-backed securities |  |
Less than 12 months |  |
Gross Unrealized Losses | (12,056) | (5,534)
Estimated Fair Value | 188,447 | 261,404
12 months or more |  |
Gross Unrealized Losses | (17,585) | (1,540)
Estimated Fair Value | 176,659 | 36,587
Total |  |
Gross Unrealized Losses | (29,641) | (7,074)
Estimated Fair Value | 365,106 | 297,991
Utah Housing Corporation bonds |  |
Less than 12 months |  |
Gross Unrealized Losses | (77) | 0
Estimated Fair Value | 4,849 | 0
12 months or more |  |
Gross Unrealized Losses | 0 | 0
Estimated Fair Value | 0 | 0
Total |  |
Gross Unrealized Losses | (77) | 0
Estimated Fair Value | 4,849 | 0
U.S. government-sponsored enterprises and Treasuries |  |
Less than 12 months |  |
Gross Unrealized Losses | (61,996) | (11,892)
Estimated Fair Value | 1,647,055 | 1,199,367
12 months or more |  |
Gross Unrealized Losses | (1,834) | 0
Estimated Fair Value | 63,176 | 0
Total |  |
Gross Unrealized Losses | (63,830) | (11,892)
Estimated Fair Value | 1,710,231 | 1,199,367
Other securities |  |
Less than 12 months |  |
Gross Unrealized Losses | (3,266) | (1,563)
Estimated Fair Value | 137,845 | 132,884
12 months or more |  |
Gross Unrealized Losses | (1,913) | 0
Estimated Fair Value | 36,752 | 0
Total |  |
Gross Unrealized Losses | (5,179) | (1,563)
Estimated Fair Value | $ 174,597 | $ 132,884

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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922890-210455 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27337-111563 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=121590138&loc=SL82922954-210456 + Details
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- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922890-210455 + Details
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