Note Loans (Non-covered loans HIP in past due status, non-performing status and accruing loans past-due 90 days or more by loan class) (Parenthetical) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unearned Income	$ 149,783	$ 130,633
Loans held-for-sale, at lower of cost or fair value	51,742	132,395
Loans held-in-portfolio, net of unearned income	26,512,168	24,292,794
PUERTO RICO
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio, net of unearned income	19,823,353	18,078,058	[1]
Popular U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio, net of unearned income	6,688,815	6,214,736
Loans Held in Portfolio | Non Covered Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Pledged Financial Instruments, Not Separately Reported, Loans Receivable Pledged as Collateral	7,200,000	7,100,000
Loans-held-in portfolio served as collateral to secure credit facilities authorized with the FHLB	4,700,000	4,600,000
Loans Held in Portfolio | Non Covered Loans | FRB Discount Window
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans served as collateral to secure debt obligations	2,100,000	2,000,000
Loans Held in Portfolio | Non Covered Loans | Public Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans served as collateral to secure debt obligations	400,000	500,000
ASC Subtopic 310-30 | Non Covered Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio, net of unearned income	304,000	215,000
ASC Subtopic 310-30 | Non Covered Loans | PUERTO RICO
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio, net of unearned income	218,000	118,000
ASC Subtopic 310-30 | Non Covered Loans | Popular U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-in-portfolio, net of unearned income	$ 86,000	$ 97,000

[1] Excludes covered loans acquired in the Westernbank FDIC-assisted transaction.