Income Taxes (Reconciliation of Statutory U.S. Corporate Federal Income Tax Rate to Effective Income Tax Rate) (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S. federal income tax rate	21.00%	21.00%	35.00%
Changes in rate due to:
U.S. tax cost/(benefit) - Tax Cuts & Jobs Act	0.30%	(2.50%)	11.00%
U.S./foreign tax differential	2.90%	3.30%	9.30%
U.S. current tax benefit on foreign exchange realization	0.00%	0.00%	(4.90%)
U.S. state and local taxes	(0.70%)	(1.00%)	(2.30%)
U.S. tax benefit on foreign dividends	(0.90%)	(0.40%)	(1.90%)
U.S. state and local taxes	1.30%	0.50%	1.10%
U.S. deferred tax benefit on foreign income			(0.60%)
Other	(0.30%)		2.60%
Effective income tax rate	23.60%	20.90%	30.70%