Reinsurance (Reinsurance amounts included in the Statements of Financial Position) (Details) - USD ($) $ in Thousands	Sep. 30, 2020		Dec. 31, 2019
Effects of Reinsurance [Line Items]
Reinsurance recoverables	$ 790,715		$ 621,510
Deferred policy acquisition costs	4,106,676	[1]	4,455,683
Deferred sales inducements	700,553		812,724
Value of business acquired	26,818		30,025
Other assets	428,808		139,933
Policyholders’ account balances	7,708,608		6,180,359
Reinsurance payables	188,463		235,318
Other liabilities	669,814	[1]	447,405
Impacts of Reinsurance
Effects of Reinsurance [Line Items]
Reinsurance recoverables	790,715		621,510
Deferred policy acquisition costs	3,382,501		3,725,719
Deferred sales inducements	368,470		437,594
Value of business acquired	(2,120)		(2,275)
Other assets	43,804		65,819
Policyholders’ account balances	3,301,271		3,253,474
Future policy benefits	15,676,899		8,328,777
Reinsurance payables	188,463		235,318
Other liabilities	582,105		337,909
Unaffiliated activity
Effects of Reinsurance [Line Items]
Reinsurance recoverables	500		200
Other assets	(19,600)		(3,900)
Reinsurance payables	1,500		1,500
Other liabilities	$ 318,300		$ 60,400

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