Reinsurance (Reinsurance amounts included in the Statement of Financial Position) (Details) - USD ($) $ in Thousands	Jun. 30, 2020		Dec. 31, 2019
Effects of Reinsurance [Line Items]
Reinsurance recoverables	$ 4,310,574		$ 3,200,642
Policy loans	(213,467)		(211,986)
Deferred policy acquisition costs	(203,125)		(178,813)
Other assets	22,948		21,203
Other liabilities	156,347	[1]	140,628
Impacts of Reinsurance
Effects of Reinsurance [Line Items]
Reinsurance recoverables	4,310,574		3,200,642
Policy loans	(21,366)		(18,627)
Deferred policy acquisition costs	(692,414)		(736,575)
Deferred sales inducements	(42,906)		(47,423)
Other assets	16,629		16,540
Other liabilities	110,493		93,557
Unaffiliated activity
Effects of Reinsurance [Line Items]
Reinsurance recoverables	$ 1,000		$ 4,000

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