Fair Value - Level 3 Unobservable Inputs, Mortgage Servicing Rights - Initial Recognition (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2023 USD ($) item	Mar. 31, 2022 USD ($) item	Dec. 31, 2022 USD ($) item
Mortgage servicing rights
Inputs
Amount recognized | $	$ 286,533,000	$ 616,302,000
Total | Mortgage servicing rights | Level 3 | Minimum
Inputs:
Annual per-loan cost of servicing | $	68		$ 68
Total | Mortgage servicing rights | Level 3 | Maximum
Inputs:
Annual per-loan cost of servicing | $	144		144
Total | Mortgage servicing rights | Level 3 | Weighted average
Inputs:
Annual per-loan cost of servicing | $	$ 108		$ 109
Total | Mortgage servicing rights | Pricing spread | Level 3 | Minimum
Inputs:
Input	4.9		4.9
Total | Mortgage servicing rights | Pricing spread | Level 3 | Maximum
Inputs:
Input	14.2		14.3
Total | Mortgage servicing rights | Pricing spread | Level 3 | Weighted average
Inputs:
Input	6.5		6.5
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Minimum
Inputs:
Input	5.2		5.0
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Maximum
Inputs:
Input	18.0		17.7
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Weighted average
Inputs:
Input	8.2		7.5
Total | Mortgage servicing rights | Life | Level 3 | Minimum
Inputs:
Input	3.7		3.7
Total | Mortgage servicing rights | Life | Level 3 | Maximum
Inputs:
Input	9.0		9.3
Total | Mortgage servicing rights | Life | Level 3 | Weighted average
Inputs:
Input	8.1		8.4
Total | MSRs at the time of initial recognition, excluding MSR purchases | Level 3
Inputs
Amount recognized | $	$ 286,533,000	616,302,000
Unpaid principal balance of underlying loans | $	$ 13,695,364,000	$ 30,575,969,000
Weighted-average servicing fee rate (as a percent)	0.50%	0.43%
Total | MSRs at the time of initial recognition, excluding MSR purchases | Level 3 | Minimum
Inputs:
Annual per-loan cost of servicing | $	$ 68	$ 80
Total | MSRs at the time of initial recognition, excluding MSR purchases | Level 3 | Maximum
Inputs:
Annual per-loan cost of servicing | $	125	177
Total | MSRs at the time of initial recognition, excluding MSR purchases | Level 3 | Weighted average
Inputs:
Annual per-loan cost of servicing | $	$ 103	$ 104
Total | MSRs at the time of initial recognition, excluding MSR purchases | Pricing spread | Level 3 | Minimum
Inputs:
Input	5.5	5.8
Total | MSRs at the time of initial recognition, excluding MSR purchases | Pricing spread | Level 3 | Maximum
Inputs:
Input	11.7	16.1
Total | MSRs at the time of initial recognition, excluding MSR purchases | Pricing spread | Level 3 | Weighted average
Inputs:
Input	7.7	7.5
Total | MSRs at the time of initial recognition, excluding MSR purchases | Annual total prepayment speed | Level 3 | Minimum
Inputs:
Input	9.2	6.0
Total | MSRs at the time of initial recognition, excluding MSR purchases | Annual total prepayment speed | Level 3 | Maximum
Inputs:
Input	23.2	23.4
Total | MSRs at the time of initial recognition, excluding MSR purchases | Annual total prepayment speed | Level 3 | Weighted average
Inputs:
Input	11.7	8.3
Total | MSRs at the time of initial recognition, excluding MSR purchases | Life | Level 3 | Minimum
Inputs:
Input	3.0	3.7
Total | MSRs at the time of initial recognition, excluding MSR purchases | Life | Level 3 | Maximum
Inputs:
Input	8.4	8.8
Total | MSRs at the time of initial recognition, excluding MSR purchases | Life | Level 3 | Weighted average
Inputs:
Input	7.3	8.3