Balance Sheet Offsetting - Summary of Valley's Financial Instruments that are Eligible for Offset (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Offsetting Liabilities
Gross Amounts Recognized	$ 206,911	$ 525,752
Gross Amounts Offset	0	0
Net Amounts Presented	206,911	525,752
Gross Amounts Not Offset, Financial Instruments	(5,268)	(8,942)
Gross Amounts Not Offset, Cash Collateral	(201,643)	(516,810)
Net Amount	0	0
Collateral posted	52,400	53,000
Repurchase agreements
Offsetting Liabilities
Gross Amounts Recognized	165,000	475,000
Gross Amounts Offset	0	0
Securities sold under agreements to repurchase	165,000	475,000
Gross Amounts Not Offset, Financial Instruments	0	0
Gross Amounts Not Offset, Cash Collateral	(165,000)	(475,000)
Net Amount	0	0
Interest rate caps and swaps
Offsetting Assets
Gross Amounts Recognized	26,087	33,570
Gross Amounts Offset	0	0
Net Amounts Presented	26,087	33,570
Gross Amounts Not Offset, Financial Instruments	(5,268)	(8,942)
Gross Amounts Not Offset, Cash Collateral	0	0
Net Amount	20,819	24,628
Offsetting Liabilities
Gross Amounts Recognized	41,911	50,752
Gross Amounts Offset	0	0
Net Amounts Presented	41,911	50,752
Gross Amounts Not Offset, Financial Instruments	(5,268)	(8,942)
Gross Amounts Not Offset, Cash Collateral	(36,643)	(41,810)
Net Amount	$ 0	$ 0