Income Taxes - Additional Information (Detail) - Subsegments [Domain] - Scenario, Unspecified [Domain] - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Income Taxes [Line Items]
Deferred Tax Assets Net	$ 1,286,086,000		$ 1,286,086,000		$ 812,819,000
Unrecognized Tax Benefits Interest On Income Taxes Accrued	2,900,000		2,900,000		3,100,000
Unrecognized Tax Benefits That Would Impact Effective Tax Rate	10,000,000		10,000,000		9,800,000
Significant Change In Unrecognized Tax Benefits Is Reasonably Possible Amount Of Unrecorded Benefit	5,800,000		5,800,000
Unrecognized Tax Benefits Current Interest On Income Taxes Accrued	325,000		325,000		540,000
Deferred Tax Liabilities	174,567,000		174,567,000		158,049,000
Deferred Tax Assets Valuation Allowance	672,391,000		672,391,000		1,212,748,000
Fixed Rate 700 Percent Notes Due July 2019 [Member]
Income Taxes [Line Items]
Senior Long Term Notes	450,000,000		450,000,000		450,000,000
Other Liabilities Member
Income Taxes [Line Items]
Deferred Tax Liabilities	649,000		649,000		$ 34,000,000
PUERTO RICO
Income Taxes [Line Items]
Deferred Tax Assets Net	776,000,000		776,000,000
Income Tax Expense Benefit	(533,533,000)	$ (4,124,000)	(500,964,000)	$ 19,140,000
Income Tax Reconciliation, Change in Deferred Tax Assets Valuation Allowance	(542,706,000)	(7,211,000)	(537,067,000)	$ (14,183,000)
PUERTO RICO | Westernbank Assets Capital Gain Treatment [Member] | Closing Agreement with the Puerto Rico Department of Treasury [Member]
Income Taxes [Line Items]
Income Tax Expense Benefit		$ 23,400,000
UNITED STATES
Income Taxes [Line Items]
Deferred Tax Assets Net	1,200,000,000		1,200,000,000
Income Tax Reconciliation, Change in Deferred Tax Assets Valuation Allowance	544,900,000
Parent Company [Member] | PUERTO RICO
Income Taxes [Line Items]
Deferred Tax Assets Valuation Allowance	$ 28,000,000		$ 28,000,000