Variable interest entities ("VIEs") - Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 34,601	$ 38,405	$ 36,696
Other assets	136,633	151,924
Assets	3,815,278	3,722,415
Total liabilities	2,849,637	$ 2,725,386
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Cash and cash equivalents	250		250
Other assets	18,350		18,350
Assets	18,600		18,600
Other liabilities	34		34
Total liabilities	$ 34		$ 34