Schedule II. Condensed Financial Information of Registrant - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Assets:
Short-term investments	$ 314,711	$ 85,035
Total investments	20,470,009	19,571,563
Cash	144,704	165,325
Other receivables	768,592	691,907
Other assets	1,667,987	1,391,560
Total assets	30,813,692	29,076,181
Liabilities:
Short-term debt	304,656	415,401
Long-term debt	2,320,793	2,324,251
Other liabilities	840,807	583,424
Total liabilities	24,839,113	23,770,661
Shareholders' equity:
Preferred stock	0	0
Common stock	92,218	97,218
Additional paid-in-capital	536,363	527,795
Accumulated other comprehensive income	(1,771,444)	(2,029,720)
Retained earnings	8,546,807	8,002,521
Total shareholders' equity	5,974,579	5,305,520	$ 4,486,803	$ 3,949,577
Total liabilities and shareholders' equity	30,813,692	29,076,181
Parent Company
Assets:
Long-term investments	32,677	39,404
Short-term investments	28,006	29,005
Total investments	60,683	68,409
Cash	62,865	66,770
Investment in affiliates	8,541,107	7,740,073
Taxes receivable from affiliates	4,310	15,202
Total assets	8,949,447	8,362,118
Liabilities:
Short-term debt	304,656	415,401
Long-term debt	2,470,459	2,473,874
Total liabilities	2,974,868	3,056,598
Shareholders' equity:
Preferred stock	351	351
Common stock	92,218	97,218
Additional paid-in-capital	886,874	878,306
Accumulated other comprehensive income	(1,771,444)	(2,029,720)
Retained earnings	8,546,807	8,002,521
Treasury stock	(1,780,227)	(1,643,156)
Total shareholders' equity	5,974,579	5,305,520
Total liabilities and shareholders' equity	8,949,447	8,362,118
Parent Company | Related Party
Assets:
Other receivables	68,127	278,301
Liabilities:
Other liabilities	36,370	52,568
Parent Company | Nonrelated Party
Assets:
Other assets	212,355	193,363
Liabilities:
Other liabilities	$ 163,383	$ 114,755