Business Segments - Assets by Segment (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Cash and invested assets	$ 22,850,154	$ 22,547,498
Accrued investment income	251,307	248,991
Deferred acquisition costs	4,914,728	4,595,444	$ 4,341,941	$ 4,137,925
Goodwill	481,791	441,591
Other assets	1,270,068	1,213,207
Total assets	29,768,048	29,046,731
Other
Segment Reporting, Asset Reconciling Item [Line Items]
Cash and invested assets	0	0
Accrued investment income	0	0
Deferred acquisition costs	0	0
Goodwill	0	0
Other assets	1,270,068	1,213,207
Total assets	1,270,068	1,213,207
Life | Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Cash and invested assets	0	0
Accrued investment income	0	0
Deferred acquisition costs	4,236,401	3,982,158
Goodwill	309,609	309,609
Other assets	0	0
Total assets	4,546,010	4,291,767
Health | Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Cash and invested assets	0	0
Accrued investment income	0	0
Deferred acquisition costs	675,871	610,071
Goodwill	172,182	131,982
Other assets	0	0
Total assets	848,053	742,053
Annuity | Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Cash and invested assets	0	0
Accrued investment income	0	0
Deferred acquisition costs	2,456	3,215
Goodwill		0
Other assets	0	0
Total assets	2,456	3,215
Investment | Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Cash and invested assets	22,850,154	22,547,498
Accrued investment income	251,307	248,991
Deferred acquisition costs	0	0
Goodwill	0	0
Other assets	0	0
Total assets	$ 23,101,461	$ 22,796,489