Reinsurance (Narrative) (Details) - USD ($) $ in Thousands							3 Months Ended			9 Months Ended			21 Months Ended	24 Months Ended	36 Months Ended			48 Months Ended
	Jul. 01, 2019	Dec. 31, 2013	Jul. 01, 2012	Dec. 31, 2010	Dec. 31, 2009	Jan. 31, 2001	Sep. 30, 2020		Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019	Dec. 31, 2016	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2016	Dec. 31, 2013	Dec. 31, 2017	Dec. 31, 2013
Effects of Reinsurance [Line Items]
Ceded Premiums							$ (450,755)		$ (466,593)	$ (1,373,498)		$ (1,379,545)
Reinsurance recoverables							51,051,073	[1]		51,051,073	[1]			$ 40,710,159	$ 40,710,159
PAR U
Effects of Reinsurance [Line Items]
Reinsurance recoverables							13,106,456			13,106,456				12,380,683	12,380,683
PURC
Effects of Reinsurance [Line Items]
Reinsurance recoverables							5,212,049			5,212,049				4,692,769	4,692,769
PARCC
Effects of Reinsurance [Line Items]
Reinsurance recoverables							2,519,113			2,519,113				2,627,595	2,627,595
GUL Re
Effects of Reinsurance [Line Items]
Reinsurance recoverables							2,498,242			2,498,242				2,292,638	2,292,638
PAR Term
Effects of Reinsurance [Line Items]
Reinsurance recoverables							1,884,370			1,884,370				1,825,594	1,825,594
Prudential of Taiwan
Effects of Reinsurance [Line Items]
Reinsurance recoverables							1,590,112			1,590,112				1,499,685	1,499,685
Term Re
Effects of Reinsurance [Line Items]
Reinsurance recoverables							1,689,778			1,689,778				1,506,366	1,506,366
Prudential Insurance
Effects of Reinsurance [Line Items]
Reinsurance recoverables							2,687,057			2,687,057				1,764,512	1,764,512
DART
Effects of Reinsurance [Line Items]
Reinsurance recoverables							468,851			468,851				$ 327,235	$ 327,235
Union Hamilton Reinsurance, Ltd.
Effects of Reinsurance [Line Items]
Reinsurance recoverables							$ 2,900,000			$ 2,900,000
Union Hamilton Reinsurance, Ltd. | Quote Share Reinsurance
Effects of Reinsurance [Line Items]
Reinsurance Retention Policy, Reinsured Risk, Percentage													50.00%
Affiliated Entity | PAR U
Effects of Reinsurance [Line Items]
Reinsurance Retention Policy, Reinsured Risk, Percentage			95.00%	70.00%
Affiliated Entity | PURC
Effects of Reinsurance [Line Items]
Reinsurance Retention Policy, Reinsured Risk, Percentage																95.00%	70.00%
Affiliated Entity | PARCC
Effects of Reinsurance [Line Items]
Reinsurance Retention Policy, Reinsured Risk, Percentage	100.00%				90.00%
Ceded Premiums	$ (476,000)
Ceded Expenses	$ (409,000)
Affiliated Entity | GUL Re
Effects of Reinsurance [Line Items]
Reinsurance Retention Policy, Reinsured Risk, Percentage		30.00%													95.00%
Affiliated Entity | PAR Term
Effects of Reinsurance [Line Items]
Reinsurance Retention Policy, Reinsured Risk, Percentage	100.00%																		95.00%
Ceded Premiums	$ (150,000)
Ceded Expenses	$ (115,000)
Affiliated Entity | Prudential of Taiwan
Effects of Reinsurance [Line Items]
Related Party Transaction, Term						2 years
Affiliated Entity | Term Re
Effects of Reinsurance [Line Items]
Reinsurance Retention Policy, Reinsured Risk, Percentage																		95.00%
Affiliated Entity | Prudential Insurance
Effects of Reinsurance [Line Items]
Reinsurance Retention Policy, Reinsured Risk, Percentage										100.00%
Affiliated Entity | DART
Effects of Reinsurance [Line Items]
Reinsurance Retention Policy, Reinsured Risk, Percentage														95.00%

[1] September 30, 2020 amounts include the impacts of the January 1, 2020 adoption of ASU 2016-13. See Note 2 for details.