Balance Sheet Offsetting - Gross Presentation Effects of Offsetting and Net Presentation of Valley's Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Offsetting Liabilities
Gross Amounts Recognized, Total Liabilities	$ 452,026	$ 428,239
Gross Amounts Offset, Total Liabilities	0	0
Net Amounts Presented, Total Liabilities	452,026	428,239
Gross Amounts Not Offset, Financial Instruments	(10,721)	(8,504)
Gross Amounts Not Offset, Cash Collateral	(441,305)	(419,735)
Net Amount, Total	0	0
Repurchase Agreements
Offsetting Liabilities
Gross Amounts Recognized, Liabilities	395,000	395,000
Gross Amounts Offset, Liabilities	0	0
Net Amounts Presented, Liabilities	395,000	395,000
Gross Amounts Not Offset, Liabilities	0	0
Gross Amounts Not Offset, Liabilities	(395,000)	(395,000)
Net Amount, Liabilities	0	0
Interest Rate Caps and Swaps
Offsetting Assets
Gross Amounts Recognized, Assets	34,000	20,950
Gross Amounts Offset, Assets	0	0
Net Amounts Presented, Assets	34,000	20,950
Gross Amounts Not Offset, Financial Instruments	(10,721)	(8,504)
Gross Amounts Not Offset, Cash Collateral	0	0
Net Amount, Assets	23,279	12,446
Offsetting Liabilities
Gross Amounts Recognized, Liabilities	57,026	33,239
Gross Amounts Offset, Liabilities	0	0
Net Amounts Presented, Liabilities	57,026	33,239
Gross Amounts Not Offset, Financial Instruments	(10,721)	(8,504)
Gross Amounts Not Offset, Cash Collateral	(46,305)	(24,735)
Net Amount, Liabilities	$ 0	$ 0