Accounting Pronouncements (Effects of Adoption of ASU 2018-12 Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Statements Adjusted [Abstract]
Deferred policy acquisition costs, net	$ 123,015	$ 121,224
Assets	20,330,165	19,058,758	$ 19,002,576
Policy benefits and losses, claims and loss expenses payable	829,992	849,113
Deferred Income Tax Liabilities, Net	1,507,604	1,447,125
Total liabilities	12,698,832	11,886,313
Accumulated other comprehensive loss	(187,238)	(223,216)
Retained earnings	8,023,000	7,600,090
Stockholders' Equity Attributable to Parent	7,631,333	7,172,445
Liabilities and Equity	20,330,165	19,058,758
Operating Segments [Member] | Life Insurance [Member]
Statements Adjusted [Abstract]
Assets	$ 3,174,307	$ 2,990,903