Other Assets - Mortgage Servicing Rights - Quantitative Assumptions Used for MSRs (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Minimum
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	6.98%	6.87%
Life in years (of the MSR)	4 years 3 months 10 days	4 years 3 months 18 days
Weighted-average coupon rate (as a percent)	3.63%	3.57%
Discount rate (as a percent)	10.27%	10.40%
Maximum
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	11.34%	11.53%
Life in years (of the MSR)	7 years 2 months 4 days	7 years 2 months 19 days
Weighted-average coupon rate (as a percent)	5.75%	5.81%
Discount rate (as a percent)	10.58%	10.60%
Weighted Average
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	7.08%	7.04%
Life in years (of the MSR)	7 years 18 days	7 years 1 month 2 days
Weighted-average coupon rate (as a percent)	3.75%	3.73%
Discount rate (as a percent)	10.52%	10.52%