Carrying amount of loans accounted for pursuant to ASC310-30 (Detail) (Westernbank Puerto Rico [Member], Acquired Loans In An F D I C Assisted Transaction [Member], Covered Under Loss Sharing Agreements With F D I C [Member], A S C Subtopic 31030 [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	$ 2,367,096	[1]	$ 2,444,172	[1]	$ 2,733,122	$ 2,827,947
Less: Allowance for loan losses	(68,386)	[1]	(78,846)		(90,371)
Carrying amount, net of allowance	2,298,710	[1]	2,365,326		2,642,751
Commercial Real Estate Portfolio Segment Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	1,448,850		1,482,684
Commercial And Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	56,497		59,256
Commercial Real Estate Construction Financing Receivable Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	52,826		65,245
Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	783,448		809,977
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	25,475		27,010
Performing Financing Receivable Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	2,211,781	[1]	2,272,142	[1]	2,469,453	2,509,075
Less: Allowance for loan losses	(49,750)	[1]	(52,798)		(56,953)
Carrying amount, net of allowance	2,162,031	[1]	2,219,344		2,412,500
Performing Financing Receivable Member | Commercial Real Estate Portfolio Segment Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	1,367,926		1,392,482
Performing Financing Receivable Member | Commercial And Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	54,709		57,059
Performing Financing Receivable Member | Commercial Real Estate Construction Financing Receivable Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	24,252		32,836
Performing Financing Receivable Member | Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	740,653		764,148
Performing Financing Receivable Member | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	24,241		25,617
Nonperforming Financing Receivable Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	155,315	[1]	172,030	[1]	263,669	318,872
Less: Allowance for loan losses	(18,636)	[1]	(26,048)		(33,418)
Carrying amount, net of allowance	136,679	[1]	145,982		230,251
Nonperforming Financing Receivable Member | Commercial Real Estate Portfolio Segment Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	80,924		90,202
Nonperforming Financing Receivable Member | Commercial And Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	1,788		2,197
Nonperforming Financing Receivable Member | Commercial Real Estate Construction Financing Receivable Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	28,574		32,409
Nonperforming Financing Receivable Member | Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	42,795		45,829
Nonperforming Financing Receivable Member | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Carrying Amount	$ 1,234		$ 1,393

[1] Includes $64 million of non-covered loans accounted for pursuant to ASC 310-30.