Reinsurance (Reinsurance Recoverable by Counterparty) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 38,946,785	$ 34,682,127
PAR U
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	11,963,017	11,444,032
PALAC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	11,483,993	8,828,190
PURC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	4,371,948	4,127,455
PARCC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,480,256	2,527,690
GUL Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,110,403	2,017,810
PAR Term
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,726,036	1,678,745
Prudential Insurance
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,624,532	1,226,917
Prudential of Taiwan
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,426,279	1,414,669
Term Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,417,733	1,259,141
DART
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	220,163	119,946
Unaffiliated
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 122,425	$ 37,532