Fair Value of Assets and Liabilities - Schedule of Valuation Techniques and Significant Unobservable Inputs Used to Measure Both Recurring and Non Recurring (Details)	Sep. 30, 2025 USD ($) $ / shares year	Jun. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)	Sep. 30, 2024 USD ($)	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	$ 5,274,124,000		$ 4,141,482,000	$ 3,912,232,000
Loans held-for-investment	129,593,000			138,038,000
MSRs	190,938,000	$ 193,061,000	203,788,000	186,308,000	$ 204,610,000	$ 192,456,000
Individually assessed loans - foreclosure probable and collateral-dependent	124,966,000			124,586,000
Municipal securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	194,244,000		184,593,000	200,212,000
Measured at fair value on a recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale	333,883,000		331,261,000	461,067,000
Loans held-for-investment	129,593,000		158,795,000	138,038,000
MSRs	190,938,000		203,788,000	186,308,000
Derivative assets	208,957,000		200,027,000	255,662,000
Measured at fair value on a recurring basis: | Municipal securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	194,244,000		184,593,000	200,212,000
Measured at fair value on a non-recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	124,966,000
Other real estate owned	24,832,000
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	125,000,000.0
Level 3 | Measured at fair value on a recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale	54,726,000		60,399,000	59,063,000
Loans held-for-investment	49,220,000		34,896,000	44,775,000
MSRs	190,938,000		203,788,000	186,308,000
Derivative assets	$ 7,149,000		1,950,000	5,142,000
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Discounted cash flows
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale, measurement input	0.0514
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input	0.0514
MSRs, measurement input	0.05
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input	0.0600
MSRs, measurement input	0.20
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale, measurement input	0.0514
Loans held-for-investment, measurement input	0.0514
MSRs, measurement input	0.1043
Level 3 | Measured at fair value on a recurring basis: | Credit discount | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale, measurement input	0
Loans held-for-investment, measurement input	0
Level 3 | Measured at fair value on a recurring basis: | Credit discount | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale, measurement input	0.26
Loans held-for-investment, measurement input	0.26
Level 3 | Measured at fair value on a recurring basis: | Credit discount | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale, measurement input	0.0129
Loans held-for-investment, measurement input	0.0188
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Discounted cash flows
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input	0.0944
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input	0
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input	0.86
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input	0.0944
MSRs, measurement input	0.0944
Level 3 | Measured at fair value on a recurring basis: | Average life - delinquent loans (in years) | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input | year	1.6
Level 3 | Measured at fair value on a recurring basis: | Average life - delinquent loans (in years) | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input | year	11.7
Level 3 | Measured at fair value on a recurring basis: | Average life - delinquent loans (in years) | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input | year	5.8
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares	70
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares	200
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input	76
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares	200
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares	1,000
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input	386
Level 3 | Measured at fair value on a recurring basis: | Pull-through rate | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives, measurement input	0.06
Level 3 | Measured at fair value on a recurring basis: | Pull-through rate | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives, measurement input	1
Level 3 | Measured at fair value on a recurring basis: | Pull-through rate | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives, measurement input	0.8488
Level 3 | Measured at fair value on a recurring basis: | Municipal securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	$ 129,794,000		$ 121,607,000	$ 135,250,000
Level 3 | Measured at fair value on a non-recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	124,966,000
Other real estate owned	$ 24,832,000
Level 3 | Measured at fair value on a non-recurring basis: | Appraisal adjustment - cost of sale | Appraisal value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans - collateral based, measurement input	0.10
Other real estate owned, measurement input	0.10
Level 3 | Measured at fair value on a non-recurring basis: | Appraisal adjustment - cost of sale | Appraisal value | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans - collateral based, measurement input	0.1000
Other real estate owned, measurement input	0.1000