Reinsurance (Reinsurance Recoverable by Counterparty) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 36,106,323	$ 34,682,127
PAR U
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	11,680,401	11,444,032
PALAC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	9,622,605	8,828,190
PURC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	4,211,368	4,127,455
PARCC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,484,194	2,527,690
GUL Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,044,196	2,017,810
PAR Term
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,691,610	1,678,745
Prudential of Taiwan
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,424,669	1,414,669
Term Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,347,453	1,259,141
Prudential Insurance
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,355,025	1,226,917
DART
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	168,676	119,946
Unaffiliated
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 76,126	$ 37,532