Non-consolidated variable interest entities - Schedule of Carrying Amount and Classification of the Assets Related to the Corporation’s Variable Interests in Non-Consolidated VIEs (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025
Variable Interest Entity
Total servicing assets	$ 94,485	$ 96,356
Total other assets	1,762,221	1,705,977
Total assets	78,972,300	75,348,267	$ 76,065,090
Variable Interest Entity Not Primary Beneficiary
Variable Interest Entity
Total servicing assets	72,882	74,236
Total other assets	3,242	3,385
Total assets	76,124	77,621
Maximum exposure to loss	$ 76,124	$ 77,621