Investment Information - Restricted assets (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Restricted Assets [Line Items]
Restricted assets	$ 8,335,957	$ 8,249,732
Collateral or guarantees - affiliated transactions
Restricted Assets [Line Items]
Restricted assets	4,212,521	4,223,955
Collateral or guarantees - third party agreements
Restricted Assets [Line Items]
Restricted assets	2,847,814	2,721,160
Deposits with US regulatory authorities
Restricted Assets [Line Items]
Restricted assets	756,368	798,100
Deposits with non-US regulatory authorities
Restricted Assets [Line Items]
Restricted assets	$ 519,254	$ 506,517