Investments (Other Invested Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Other Invested Assets [Line Items]
Other invested assets	$ 1,209,925	$ 520,955
Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	887,706	458,790
Company’s investment in separate accounts
Other Invested Assets [Line Items]
Other invested assets	53,694	44,018
Derivative Instruments
Other Invested Assets [Line Items]
Other invested assets	268,525	18,147
Equity Method | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	808,227	381,998
Equity Method | Private equity | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	286,141	241,493
Equity Method | Hedge funds | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	432,749	77,311
Equity Method | Real estate-related | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	89,337	63,194
Fair Value | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	79,479	76,792
Fair Value | Private equity | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	69,137	65,436
Fair Value | Hedge funds | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	481	499
Fair Value | Real estate-related | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	$ 9,861	$ 10,857