Variable interest entities and securitization activities - Assets of Unconsolidated VIEs (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Carrying amount
Mortgage-backed securities	$ 29,546	$ 27,436
Investment in unconsolidated joint ventures	132,730	133,321
Total Assets	12,043,532	12,441,217
Unconsolidated VIEs
Carrying amount
Mortgage-backed securities	26,716	26,301
Investment in unconsolidated joint ventures	132,730	133,321
Total Assets	159,446	159,622
Maximum Exposure to Loss
Mortgage backed securities, at fair value	26,716	26,301
Investment in unconsolidated joint venture	132,730	133,321
Total assets in unconsolidated VIEs maximum exposure to loss	$ 159,446	$ 159,622