Other Assets - Components of Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Other Assets [Abstract]
Prepaid federal income taxes (Note 10)	$ 354,123	$ 210,889
Prepaid reinsurance premiums	201,674	267,638
Company-owned life insurance	113,386	115,586
Loaned securities (Notes 5 and 6)	103,996	57,499
Right-of-use assets (Note 13)	31,878	32,985
Other	32,246	30,488
Total other assets	$ 837,303	$ 715,085
Operating lease, right-of-use asset, statement of financial position [extensible enumeration]	Total other assets	Total other assets