Investments - Costs and Fair Value of Securities Classified as Trading Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Total trading securities, cost	$ 35,179	$ 16,359
Fixed Maturities
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Total trading securities, cost	35,179	16,359
Total trading securities, Fair value	$ 35,046	$ 16,300

Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Name:	us-gaap_TradingSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant