Fair Value of Assets and Liabilities - Narrative (Details)	9 Months Ended
	Sep. 30, 2025 USD ($) $ / shares	Jun. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)	Sep. 30, 2024 USD ($)	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	$ 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 measured	124,966,000			124,586,000
Non-performing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held-for-sale classified as nonaccrual	200,000		4,000,000.0	2,400,000
Mortgage loans held-for-sale classified greater than 90 days past due and still accruing	53,800,000		59,300,000	58,400,000
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	5,274,124,000		4,141,482,000	3,912,232,000
Remaining contractual principal balance outstanding, mortgage loans held-for-sale	339,100,000		335,900,000	462,200,000
Remaining contractual principal balance outstanding, mortgage loans held-for-investment	$ 126,400,000		157,800,000	138,800,000
Appraisal adjustment - cost of sale | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned, measurement input	0.10
Weighted Average | Loans held-for- investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Life of loans	5 years 9 months 18 days
Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	$ 194,244,000		184,593,000	200,212,000
Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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 asset	208,957,000		200,027,000	255,662,000
Measured at fair value on a recurring basis: | Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	194,244,000		184,593,000	200,212,000
Measured at fair value on a non-recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually measured	124,966,000
Other real estate owned	24,832,000
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually measured	125,000,000.0
Level 3 | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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 asset	$ 7,149,000		1,950,000	5,142,000
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Measurement Input, Discount Rate | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input	0.1043
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Constant prepayment rate (CPR) - current loans | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input	0.0944
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Cost of servicing | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input	76
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Cost of servicing - delinquent | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input	386
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Pull-through rate | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, measurement input	0.8488
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Mortgage loans held-for-sale | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.0514
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Mortgage loans held-for-sale | Credit discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.0129
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Loans held-for- investment | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.0514
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Loans held-for- investment | Credit discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.0188
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Loans held-for- investment | Constant prepayment rate (CPR) - current loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.0944
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Mortgage servicing rights | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.1043
Level 3 | Measured at fair value on a recurring basis: | Weighted Average | Mortgage servicing rights | Constant prepayment rate (CPR) - current loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.0944
Level 3 | Measured at fair value on a recurring basis: | Minimum | Measurement Input, Discount Rate | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input	0.05
Level 3 | Measured at fair value on a recurring basis: | Minimum | Constant prepayment rate (CPR) - current loans | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input	0
Level 3 | Measured at fair value on a recurring basis: | Minimum | Cost of servicing | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input | $ / shares	70
Level 3 | Measured at fair value on a recurring basis: | Minimum | Cost of servicing - delinquent | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input | $ / shares	200
Level 3 | Measured at fair value on a recurring basis: | Minimum | Pull-through rate | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, measurement input	0.06
Level 3 | Measured at fair value on a recurring basis: | Minimum | Mortgage loans held-for-sale | Credit discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0
Level 3 | Measured at fair value on a recurring basis: | Minimum | Loans held-for- investment | Credit discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0
Level 3 | Measured at fair value on a recurring basis: | Minimum | Mortgage servicing rights | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.05
Level 3 | Measured at fair value on a recurring basis: | Minimum | Mortgage servicing rights | Constant prepayment rate (CPR) - current loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0
Level 3 | Measured at fair value on a recurring basis: | Maximum | Measurement Input, Discount Rate | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input	0.20
Level 3 | Measured at fair value on a recurring basis: | Maximum | Constant prepayment rate (CPR) - current loans | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input	0.86
Level 3 | Measured at fair value on a recurring basis: | Maximum | Cost of servicing | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input | $ / shares	200
Level 3 | Measured at fair value on a recurring basis: | Maximum | Cost of servicing - delinquent | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input | $ / shares	1,000
Level 3 | Measured at fair value on a recurring basis: | Maximum | Pull-through rate | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, measurement input	1
Level 3 | Measured at fair value on a recurring basis: | Maximum | Mortgage loans held-for-sale | Credit discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.26
Level 3 | Measured at fair value on a recurring basis: | Maximum | Loans held-for- investment | Credit discount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.26
Level 3 | Measured at fair value on a recurring basis: | Maximum | Mortgage servicing rights | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.20
Level 3 | Measured at fair value on a recurring basis: | Maximum | Mortgage servicing rights | Constant prepayment rate (CPR) - current loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.86
Level 3 | Measured at fair value on a recurring basis: | Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	$ 129,794,000		$ 121,607,000	$ 135,250,000
Level 3 | Measured at fair value on a non-recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually measured	124,966,000
Other real estate owned	$ 24,832,000