Reinsurance (Reinsurance amounts included in the Statements of Financial Position) (Details) - USD ($) $ in Thousands	Jun. 30, 2020		Dec. 31, 2019
Effects of Reinsurance [Line Items]
Reinsurance recoverables	$ 860,518		$ 621,510
Deferred policy acquisition costs	4,243,190	[1]	4,455,683
Deferred sales inducements	751,671		812,724
Value of business acquired	27,246		30,025
Other assets	312,198		139,933
Policyholders’ account balances	6,859,669		6,180,359
Future policy benefits	25,263,142		12,932,461
Reinsurance payables	210,579		235,318
Other liabilities	893,740	[1]	447,405
Impacts of Reinsurance
Effects of Reinsurance [Line Items]
Reinsurance recoverables	860,518		621,510
Deferred policy acquisition costs	3,530,644		3,725,719
Deferred sales inducements	397,925		437,594
Value of business acquired	(2,135)		(2,275)
Other assets	52,143		65,819
Policyholders’ account balances	3,322,132		3,253,474
Future policy benefits	17,724,091		8,328,777
Reinsurance payables	210,579		235,318
Other liabilities	489,594		337,909
Unaffiliated activity
Effects of Reinsurance [Line Items]
Reinsurance recoverables	500		200
Other assets	(13,300)		(3,900)
Reinsurance payables	100		100
Other liabilities	$ 214,300		$ 60,400

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