v3.26.3
Investments - Gross Unrealized Losses and Fair Value for Mortgage-Backed in Unrealized Loss Position (Details) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Less than 12 months    
Gross Unrealized Losses $ (35,198) $ (195)
Estimated Fair Value 2,163,315 22,809
12 months or more    
Gross Unrealized Losses (79,245) (71,532)
Estimated Fair Value 427,875 1,036,556
Total    
Gross Unrealized Losses (114,443) (71,727)
Estimated Fair Value 2,591,190 1,059,365
Mortgage-backed securities    
Less than 12 months    
Gross Unrealized Losses (16,320) (164)
Estimated Fair Value 271,139 10,896
12 months or more    
Gross Unrealized Losses (69,861) (54,207)
Estimated Fair Value 237,898 275,703
Total    
Gross Unrealized Losses (86,181) (54,371)
Estimated Fair Value 509,037 286,599
Utah Housing Corporation bonds    
Less than 12 months    
Gross Unrealized Losses 0 0
Estimated Fair Value 0 0
12 months or more    
Gross Unrealized Losses (346) (334)
Estimated Fair Value 1,861 2,156
Total    
Gross Unrealized Losses (346) (334)
Estimated Fair Value 1,861 2,156
U.S. government-sponsored enterprises and Treasuries    
Less than 12 months    
Gross Unrealized Losses (13,082) 0
Estimated Fair Value 1,526,218 0
12 months or more    
Gross Unrealized Losses (885) (9,581)
Estimated Fair Value 98,843 639,506
Total    
Gross Unrealized Losses (13,967) (9,581)
Estimated Fair Value 1,625,061 639,506
Other securities    
Less than 12 months    
Gross Unrealized Losses (5,796) (31)
Estimated Fair Value 365,958 11,913
12 months or more    
Gross Unrealized Losses (8,153) (7,410)
Estimated Fair Value 89,273 119,191
Total    
Gross Unrealized Losses (13,949) (7,441)
Estimated Fair Value $ 455,231 $ 131,104