Reinsurance (Reinsurance Recoverable by Counterparty) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 40,693,991	$ 38,709,651
PAR U
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	18,630,892	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	2,123,485	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	1,987,253	2,101,004
Prudential Insurance
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	4,164,836	1,311,525
Term Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,980,014	2,080,564
Lotus Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,077,391	2,051,831
DART
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	765,376	744,043
PURE
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	7,383,771	0
Unaffiliated activity
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 1,580,973	$ 1,616,486