Investments (Other Invested Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Other Invested Assets [Line Items]
Other invested assets	$ 94,079	$ 818,810
LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	90,950	624,559
Derivative Instruments
Other Invested Assets [Line Items]
Other invested assets	3,129	194,251
Equity Method | LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	81,002	613,947
Equity Method | Private equity | LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	18,829	28,955
Equity Method | Hedge funds | LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	0	340,951
Equity Method | Real estate-related | LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	62,173	244,041
Fair Value | LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	9,948	10,612
Fair Value | Private equity | LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	4,028	4,220
Fair Value | Hedge funds | LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	166	172
Fair Value | Real estate-related | LPs/LLCs
Other Invested Assets [Line Items]
Other invested assets	$ 5,754	$ 6,220