Balance Sheet Offsetting - Summary of Valley's Financial Instruments that are Eligible for Offset (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Derivatives And Hedging Activities [Line Items]
Gross Amounts Recognized, Total	$ 428,239		$ 540,439
Gross Amounts Offset, Total	0		0
Net Amounts Presented, Total	428,239		540,439
Net Amount, Total	0		0
Interest rate caps and swaps, asset
Derivatives And Hedging Activities [Line Items]
Gross Amounts Recognized, Assets	20,950		14,805
Gross Amounts Offset, Assets	0		0
Net Amounts Presented, Assets	20,950		14,805
Gross Amounts Not Offset, Assets	12,446		6,521
Interest rate caps and swaps, liability
Derivatives And Hedging Activities [Line Items]
Gross Amounts Recognized, Liabilities	33,239		20,439
Gross Amounts Offset, Liabilities	0		0
Net Amounts Presented, Liabilities	33,239		20,439
Net Amount, Liabilities	0		0
Repurchase agreements
Derivatives And Hedging Activities [Line Items]
Gross Amounts Recognized, Liabilities	395,000		520,000
Gross Amounts Offset, Liabilities	0		0
Securities sold under agreements to repurchase	395,000		520,000
Net Amount, Liabilities	0		0
Financial Instruments
Derivatives And Hedging Activities [Line Items]
Gross Amounts Not Offset, Total	(8,504)		(8,284)
Financial Instruments | Interest rate caps and swaps, asset
Derivatives And Hedging Activities [Line Items]
Gross Amounts Not Offset, Assets	(8,504)		(8,284)
Financial Instruments | Interest rate caps and swaps, liability
Derivatives And Hedging Activities [Line Items]
Gross Amounts Not Offset, Liabilities	(8,504)		(8,284)
Financial Instruments | Repurchase agreements
Derivatives And Hedging Activities [Line Items]
Gross Amounts Not Offset, Liabilities	0		0
Cash Collateral
Derivatives And Hedging Activities [Line Items]
Gross Amounts Not Offset, Total	(370,265)		(532,155)
Cash Collateral | Interest rate caps and swaps, asset
Derivatives And Hedging Activities [Line Items]
Gross Amounts Not Offset, Assets	0		0
Cash Collateral | Interest rate caps and swaps, liability
Derivatives And Hedging Activities [Line Items]
Gross Amounts Not Offset, Liabilities	24,735		(12,155)
Cash Collateral | Repurchase agreements
Derivatives And Hedging Activities [Line Items]
Gross Amounts Not Offset, Liabilities	$ (395,000)	[1]	$ (520,000)	[1]

[1] * Represents fair value of non-cash pledged investment securities.