Reinsurance (Reinsurance Recoverable by Counterparty) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 42,921,981	$ 34,682,127
PAR U
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	12,277,299	11,444,032
PALAC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	14,077,766	8,828,190
PURC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	4,510,249	4,127,455
PARCC
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,666,372	2,527,690
GUL Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	2,211,909	2,017,810
PAR Term
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,827,497	1,678,745
Prudential Insurance
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,975,165	1,226,917
Prudential of Taiwan
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,439,389	1,414,669
Term Re
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	1,456,210	1,259,141
DART
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	275,156	119,946
Unaffiliated
Effects of Reinsurance [Line Items]
Total reinsurance recoverables	$ 204,969	$ 37,532