Fair Values of Assets and Liabilities - Schedule of Valuation Techniques and Significant Unobservable Inputs Used to Measure Both Recurring and Non Recurring (Details)	Sep. 30, 2024 USD ($) year $ / shares	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	$ 3,912,232,000		$ 3,502,915,000	$ 3,611,835,000
Loans held-for-investment	138,038,000			171,178,000
MSRs	186,308,000	$ 204,610,000	192,456,000	210,524,000	$ 200,692,000	$ 230,225,000
Individually assessed loans - foreclosure probable and collateral-dependent	124,586,000			77,937,000
Municipal securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	200,212,000		140,958,000	168,523,000
U.S. government agencies
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	47,654,000		45,124,000	72,430,000
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	124,600,000
Measured at fair value on a recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale	461,067,000		292,722,000	304,808,000
Loans held-for-investment	138,038,000		155,261,000	171,178,000
MSRs	186,308,000		192,456,000	210,524,000
Derivative assets	255,662,000		275,726,000	323,705,000
Measured at fair value on a recurring basis: | Municipal securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	200,212,000		140,958,000	168,523,000
Measured at fair value on a recurring basis: | U.S. government agencies
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	47,654,000		45,124,000	72,430,000
Measured at fair value on a recurring basis: | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale	59,063,000		26,835,000	25,187,000
Loans held-for-investment	44,775,000		60,670,000	57,961,000
MSRs	186,308,000		192,456,000	210,524,000
Derivative assets	5,142,000		4,510,000	2,516,000
Measured at fair value on a recurring basis: | Level 3 | Municipal securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	135,250,000		86,237,000	113,219,000
Measured at fair value on a recurring basis: | Level 3 | U.S. government agencies
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities	0		$ 0	$ 0
Mortgage loans held-for-sale	$ 59,063,000
Measured at fair value on a recurring basis: | Discount rate | Level 3 | Discounted cash flows
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale, measurement input	0.0614
Measured at fair value on a recurring basis: | Discount rate | Level 3 | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input	0.0612
MSRs, measurement input	0.06
Measured at fair value on a recurring basis: | Discount rate | Level 3 | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input	0.0614
MSRs, measurement input	0.20
Measured at fair value on a recurring basis: | Discount rate | Level 3 | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale, measurement input	0.0614
Loans held-for-investment, measurement input	0.0614
MSRs, measurement input	0.1096
Measured at fair value on a recurring basis: | Credit discount | Level 3 | 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
Measured at fair value on a recurring basis: | Credit discount | Level 3 | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale, measurement input	0.14
Loans held-for-investment, measurement input	0.39
Measured at fair value on a recurring basis: | Credit discount | Level 3 | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans held-for-sale, measurement input	0.0052
Loans held-for-investment, measurement input	0.0107
Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Level 3 | Discounted cash flows
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input	0.0921
Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Level 3 | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input	0.06
Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Level 3 | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input	0.90
Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) - current loans | Level 3 | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input	0.0921
MSRs, measurement input	0.0921
Measured at fair value on a recurring basis: | Average life - delinquent loans (in years) | Level 3 | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input | year	1.4
Measured at fair value on a recurring basis: | Average life - delinquent loans (in years) | Level 3 | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input | year	11.3
Measured at fair value on a recurring basis: | Average life - delinquent loans (in years) | Level 3 | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input | year	5.9
Measured at fair value on a recurring basis: | Cost of servicing | Level 3 | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares	70
Measured at fair value on a recurring basis: | Cost of servicing | Level 3 | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares	200
Measured at fair value on a recurring basis: | Cost of servicing | Level 3 | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input	76
Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Level 3 | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares	200
Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Level 3 | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares	1,000
Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Level 3 | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input	386
Measured at fair value on a recurring basis: | Pull-through rate | Level 3 | Discounted cash flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives, measurement input	0.01
Measured at fair value on a recurring basis: | Pull-through rate | Level 3 | Discounted cash flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives, measurement input	1
Measured at fair value on a recurring basis: | Pull-through rate | Level 3 | Discounted cash flows | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives, measurement input	0.8071
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	$ 124,586,000
Other real estate owned	13,682,000
Measured at fair value on a non-recurring basis: | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	124,586,000
Other real estate owned	$ 13,682,000
Measured at fair value on a non-recurring basis: | Appraisal adjustment - cost of sale | Level 3 | 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
Measured at fair value on a non-recurring basis: | Appraisal adjustment - cost of sale | Level 3 | 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