Reinsurance (Reinsurance Recoverable by Counterparty) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 43,285,050	$ 38,709,651
PAR U
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	19,642,785	15,722,061
PURC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	0	7,565,968
PARCC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,140,373	2,304,270
GUL Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	0	3,211,899
PAR Term
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,084,390	2,101,004
Prudential Insurance
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	4,901,818	1,311,525
Term Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,115,998	2,080,564
Lotus Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,102,136	2,051,831
DART
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	855,366	744,043
PURE
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	7,853,257	0
Unaffiliated activity
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 1,588,927	$ 1,616,486