Reconciliation of income tax computed at US Federal tax rates (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax [Abstract]
Statutory Income Tax	21.00%	21.00%	21.00%
Net Operating Loss Carryback	(0.70%)	(3.80%)	0.00%
Tax Exempt Income	(1.10%)	(0.80%)	(0.50%)
Tax Credits	(0.90%)	(1.30%)	(1.10%)
Policyholder Reserves	2.40%	0.70%	0.00%
Other Items, Net	1.80%	1.90%	1.00%
Effective Tax	22.50%	17.70%	20.40%