Non-consolidated VIEs - Corporation's VI in non-consolidated VIEs and max exposure to loss (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Variable Interest Entity [Line Items]
Assets	$ 67,675,759	$ 67,637,917	$ 69,525,082
Variable Interest Entity Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	104,126	105,771
Maximum exposure to loss	104,126	105,771
Variable Interest Entity Not Primary Beneficiary | Servicing assets
Variable Interest Entity [Line Items]
Assets	98,184	99,614
Variable Interest Entity Not Primary Beneficiary | Mortgage servicing rights
Variable Interest Entity [Line Items]
Assets	98,184	99,614
Variable Interest Entity Not Primary Beneficiary | Other assets
Variable Interest Entity [Line Items]
Assets	5,942	6,157
Variable Interest Entity Not Primary Beneficiary | Servicing advances
Variable Interest Entity [Line Items]
Assets	$ 5,942	$ 6,157