Note Income taxes (Differences between income tax expense (benefit) applicable to income before income taxes and amount computed by applying the statutory tax rate in Puerto Rico) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Amount
Income tax expense	$ 33,006	$ 32,265
PUERTO RICO
Amount
Computed income tax at statutory rates	49,121	45,733
Net benefit of net tax exempt interest income	(18,004)	(15,584)
Deferred tax asset valuation allowance	5,056	5,273
Difference in tax rates due to multiple jurisdictions	(959)	(864)
State and local taxes	1,279	2,927
Income tax expense	$ 33,006	$ 32,265
% of pre-tax income
Computed income tax at statutory rates	39.00%	39.00%
Net benefit of net tax exempt interest income	(14.00%)	(13.00%)
Deferred tax asset valuation allowance	4.00%	5.00%
Difference in tax rates due to multiple jurisdictions	(1.00%)	(1.00%)
State and local taxes	1.00%	3.00%
Income tax (benefit) expense	26.00%	28.00%
PUERTO RICO | Effect Of Income Subject To Preferential Tax Rate
Amount
Effect of income subject to preferential tax rate	$ (3,019)	$ (3,414)
% of pre-tax income
Others	(3.00%)	(3.00%)
PUERTO RICO | Others
Amount
Effect of income subject to preferential tax rate	$ (468)	$ (1,806)
% of pre-tax income
Others	0.00%	(2.00%)