Reconciliation of income tax computed at US Federal tax rates (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax [Abstract]
Statutory Income Tax	21.00%	21.00%	35.00%
U.S. Deferred Tax Liability Remeasurement	0.00%	0.00%	(7.00%)
Deemed Repatriation Tax on Foreign Earnings and Profit (E&P)	0.00%	1.80%	4.70%
Tax Exempt Income	(0.50%)	(1.30%)	(0.80%)
Tax Credits	(1.10%)	(2.40%)	(1.50%)
Policyholder Reserves	0.00%	(2.40%)	0.00%
Other Items, Net	1.00%	(0.10%)	(1.20%)
Effective Tax	20.40%	16.60%	29.20%