Investments - Schedule of Components of Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	$ 353,631	$ 348,518	$ 404,860
Less investment expenses	2,420	2,762	2,412
Net investment income (excluding derivatives and trading securities)	351,211	345,756	402,448
Net investment income	299,640	562,530	417,202
Debt and equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	298,965	309,082	373,479
Mortgage loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	20,691	20,155	13,162
Policy loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	2,626	2,667	3,361
Short-term investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	3,940	293	2,160
Other investment assets
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	27,409	16,321	12,698
Index option derivative gain (loss)
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Index option derivative gain (loss)	(86,866)	120,718	14,754
Embedded derivative on reinsurance
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	250,230	84,725	0
Trading securities market adjustments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ (214,935)	$ 11,331	$ 0