Policyholders' Liabilities (Future Policy Benefits) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Liability for Future Policy Benefit, by Product Segment [Line Items]
Individual and group annuities and supplementary contracts	$ 677,266	$ 609,457
Other contract liabilities	8,565,341	5,626,920
Total future policy benefits	25,258,673	19,476,394
Domestic
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life insurance	14,522,350	11,831,419
Taiwan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life insurance	$ 1,493,716	$ 1,408,598