Mortgage Servicing Rights - Quantitative Assumptions Used for MSRs (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Minimum
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	6.89%	7.02%
Life in years (of the MSR)	4 years 3 months 3 days	3 years 4 months 6 days
Weighted-average coupon rate (as a percent)	3.57%	3.55%
Discount rate (as a percent)	10.36%	10.41%
Maximum
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	11.27%	13.58%
Life in years (of the MSR)	7 years 3 months	7 years 4 months 13 days
Weighted-average coupon rate (as a percent)	5.84%	6.24%
Discount rate (as a percent)	10.55%	10.54%
Weighted Average
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	7.02%	7.11%
Life in years (of the MSR)	7 years 1 month 9 days	7 years 2 months 12 days
Weighted-average coupon rate (as a percent)	3.70%	3.68%
Discount rate (as a percent)	10.52%	10.51%