Investments (Other Invested Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Other Invested Assets [Line Items]
Other invested assets	$ 1,117,460	$ 1,209,925
Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	914,251	887,706
Company’s investment in separate accounts
Other Invested Assets [Line Items]
Other invested assets	793	53,694
Derivative Instruments
Other Invested Assets [Line Items]
Other invested assets	202,416	268,525
Equity Method | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	835,556	808,227
Equity Method | Private equity | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	298,562	286,141
Equity Method | Hedge funds | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	440,490	432,749
Equity Method | Real estate-related | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	96,504	89,337
Fair Value | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	78,695	79,479
Fair Value | Private equity | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	67,984	69,137
Fair Value | Hedge funds | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	481	481
Fair Value | Real estate-related | Total LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	$ 10,230	$ 9,861