Balance Sheet Offsetting - Gross Presentation Effects of Offsetting and Net Presentation of Valley's Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Offsetting Liabilities
Gross Amounts Recognized, Total Liabilities	$ 336,889	$ 525,752
Gross Amounts Offset, Total Liabilities	0	0
Net Amounts Presented, Total Liabilities	336,889	525,752
Gross Amounts Not Offset, Financial Instruments	0	(8,942)
Gross Amounts Not Offset, Cash Collateral	(336,889)	(516,810)
Net Amount, Total	0	0
Repurchase Agreements
Offsetting Liabilities
Gross Amounts Recognized, Liabilities	265,000	475,000
Gross Amounts Offset, Liabilities	0	0
Net Amounts Presented, Liabilities	265,000	475,000
Gross Amounts Not Offset, Liabilities	0	0
Gross Amounts Not Offset, Liabilities	(265,000)	(475,000)
Net Amount, Liabilities	0	0
Interest Rate Caps and Swaps
Offsetting Assets
Gross Amounts Recognized, Assets	45,299	33,570
Gross Amounts Offset, Assets	0	0
Net Amounts Presented, Assets	45,299	33,570
Gross Amounts Not Offset, Financial Instruments	0	(8,942)
Gross Amounts Not Offset, Cash Collateral	0	0
Net Amount, Assets	45,299	24,628
Offsetting Liabilities
Gross Amounts Recognized, Liabilities	71,889	50,752
Gross Amounts Offset, Liabilities	0	0
Net Amounts Presented, Liabilities	71,889	50,752
Gross Amounts Not Offset, Financial Instruments	0	(8,942)
Gross Amounts Not Offset, Cash Collateral	(71,889)	(41,810)
Net Amount, Liabilities	$ 0	$ 0