Note Stockholders' equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Stockholders Equity Note [Line Items]
Puerto Rico Laws Restrictions On Banks Net Income				a minimum of 10% of BPPR’s net income
Equity Restrictions	$ 513,000			$ 513,000		$ 513,000
Transfers To Statutory Reserve	$ 0		$ 0	0	$ 0
Dividends, Common Stock, Cash				$ 76,620	$ 46,666
Common Stock Dividends Per Share Declared	$ 0.25		$ 0.15	$ 0.75	$ 0.45
Dividends Payable	$ 25,500			$ 25,500
Stock Repurchase Program Authorized Amount		$ 75,000
Treasury Stock Value Acquired Cost Method				$ 77,418	$ 1,563
Total Common Shares Repurchased Accelerated Share Repurchase Agreements		1,847,372
Accelerate Share Repurchase Transaction
Stockholders Equity Note [Line Items]
Accelerated Share Repurchase Program Adjustment		$ 4,500
Treasury Stock Value Acquired Cost Method		$ 79,500