Reconciliation of income tax computed at US Federal tax rates (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax [Abstract]
Statutory Income Tax	21.00%	21.00%	21.00%
Net Operating Loss Carryback	0.00%	(0.70%)	(3.80%)
Tax Exempt Income	(1.10%)	(1.10%)	(0.80%)
Tax Credits	(0.30%)	(0.90%)	(1.30%)
Policyholder Reserves	(1.90%)	2.40%	0.70%
Other Items, Net	1.70%	1.80%	1.90%
Effective Tax	19.40%	22.50%	17.70%