Reinsurance (Reinsurance amounts included in the Statements of Financial Position) (Details) - USD ($) $ in Thousands	Mar. 31, 2020		Dec. 31, 2019
Effects of Reinsurance [Line Items]
Reinsurance recoverables	$ 53,163,489	[1]	$ 40,710,159
Policy loans	1,317,110		1,314,064
Deferred policy acquisition costs	1,991,035	[1]	1,855,698
Other assets	410,619		441,543
Future policy benefits	37,547,367	[1]	25,258,673
Other liabilities	1,436,211	[1]	1,390,876
Impacts of Reinsurance
Effects of Reinsurance [Line Items]
Reinsurance recoverables	53,163,489		40,710,159
Policy loans	(146,772)		(142,262)
Deferred policy acquisition costs	(6,700,160)		(6,989,618)
Deferred sales inducements	(441,691)		(515,968)
Other assets	246,842		258,427
Policyholders’ account balances	4,905,609		4,934,544
Future policy benefits	4,378,232		4,209,817
Other liabilities	865,622		884,641
Unaffiliated activity
Effects of Reinsurance [Line Items]
Reinsurance recoverables	422,400		156,700
Other assets	0		0
Future policy benefits	500		0
Other liabilities	$ 41,800		$ 43,100

[1] March 31, 2020 amounts include the impacts of the January 1, 2020 adoption of ASU 2016-13. See Note 2 for details.