Note Allowance for loan losses (Activity in Allowance for Loan Losses Related to ASC 310-30 Acquired Loans) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable
Balance at beginning of period	$ 537,111	$ 601,792
Provision for loan losses	(44,835)	(40,035)
Charge-offs	(59,937)	(81,815)
Recoveries	16,463	26,005
Net recovery (write-down)		2,680
Balance at end of period	538,472	588,697
Westernbank Puerto Rico | Acquired loans in an FDIC assisted transaction | Credit Impaired Loans | ASC Subtopic 310-30
Accounts, Notes, Loans and Financing Receivable
Balance at beginning of period	63,563	78,846
Provision for loan losses	1,791	8,601
Charge-offs	(2,387)	(19,061)
Balance at end of period	$ 62,967	$ 68,386