Borrowings - Additional Information (Detail) $ in Billions	Dec. 31, 2019 USD ($)
Debt Disclosure [Abstract]
Repurchase agreements and advances borrowing limit	$ 12.7
Unsecured borrowing capacity	$ 1.7

The total borrowing limit from the Federal Home Loan Bank and Federal Reserve Bank for advances, and repurchase agreements based on the level of qualifying collateral for these borrowings as at the balance sheet date.

No definition available.

Name:	pbct_RepurchaseAgreementsAndAdvanceBorrowingLimit
Namespace Prefix:	pbct_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant