Fair Value - Level 3 Unobservable Inputs, Mortgage Servicing Rights - Initial Recognition (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023 USD ($) item	Jun. 30, 2022 USD ($) item	Jun. 30, 2023 USD ($) item	Jun. 30, 2022 USD ($) item	Dec. 31, 2022 USD ($) item
Mortgage servicing rights
Inputs
Amount recognized | $	$ 562,523,000	$ 398,253,000	$ 849,056,000	$ 1,014,555,000
Total | Mortgage servicing rights | Level 3 | Minimum
Inputs:
Annual per-loan cost of servicing | $			67		$ 68
Total | Mortgage servicing rights | Level 3 | Maximum
Inputs:
Annual per-loan cost of servicing | $			130		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	5.4		5.4		4.9
Total | Mortgage servicing rights | Pricing spread | Level 3 | Maximum
Inputs:
Input	12.6		12.6		14.3
Total | Mortgage servicing rights | Pricing spread | Level 3 | Weighted average
Inputs:
Input	6.4		6.4		6.5
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Minimum
Inputs:
Input	6.3		6.3		5.0
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Maximum
Inputs:
Input	17.4		17.4		17.7
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Weighted average
Inputs:
Input	7.7		7.7		7.5
Total | Mortgage servicing rights | Life | Level 3 | Minimum
Inputs:
Input	3.2		3.2		3.7
Total | Mortgage servicing rights | Life | Level 3 | Maximum
Inputs:
Input	9.3		9.3		9.3
Total | Mortgage servicing rights | Life | Level 3 | Weighted average
Inputs:
Input	8.2		8.2		8.4
Total | MSRs at the time of initial recognition, excluding MSR purchases | Level 3
Inputs
Amount recognized | $	$ 562,523,000	398,253,000	$ 849,056,000	1,014,555,000
Unpaid principal balance of underlying loans | $	$ 24,993,118,000	$ 19,377,222,000	$ 38,688,482,000	$ 49,953,192,000
Weighted-average servicing fee rate (as a percent)	0.50%	0.42%	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	$ 68	$ 80
Total | MSRs at the time of initial recognition, excluding MSR purchases | Level 3 | Maximum
Inputs:
Annual per-loan cost of servicing | $	127	146	127	176
Total | MSRs at the time of initial recognition, excluding MSR purchases | Level 3 | Weighted average
Inputs:
Annual per-loan cost of servicing | $	$ 98	$ 103	$ 100	$ 104
Total | MSRs at the time of initial recognition, excluding MSR purchases | Pricing spread | Level 3 | Minimum
Inputs:
Input	5.5	5.7	5.5	5.7
Total | MSRs at the time of initial recognition, excluding MSR purchases | Pricing spread | Level 3 | Maximum
Inputs:
Input	12.6	11.7	12.6	16.1
Total | MSRs at the time of initial recognition, excluding MSR purchases | Pricing spread | Level 3 | Weighted average
Inputs:
Input	7.4	8.2	7.5	7.7
Total | MSRs at the time of initial recognition, excluding MSR purchases | Annual total prepayment speed | Level 3 | Minimum
Inputs:
Input	9.1	5.7	9.1	5.7
Total | MSRs at the time of initial recognition, excluding MSR purchases | Annual total prepayment speed | Level 3 | Maximum
Inputs:
Input	20.7	19.3	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	10.9	8.4	11.3	8.3
Total | MSRs at the time of initial recognition, excluding MSR purchases | Life | Level 3 | Minimum
Inputs:
Input	3.1	4.3	3.0	3.7
Total | MSRs at the time of initial recognition, excluding MSR purchases | Life | Level 3 | Maximum
Inputs:
Input	8.4	9.2	8.4	9.2
Total | MSRs at the time of initial recognition, excluding MSR purchases | Life | Level 3 | Weighted average
Inputs:
Input	7.6	8.5	7.5	8.4