Regulatory and Capital Requirements - Schedule of Actual Capital Positions and Ratios under Banking Regulations (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Total Risk-based Capital
Risk-based capital actual, amount	$ 2,258,044	$ 2,084,531
Risk-based capital actual, ratio	12.61%	12.15%
Risk-based capital minimum capital requirements, amount	$ 1,656,575	$ 1,480,006
Risk-based capital minimum capital requirements, ratio	9.25%	8.625%
Common Equity Tier 1 Capital
Common equity tier 1 capital, amount	$ 1,651,849	$ 1,590,825
Common equity tier 1 capital, ratio	9.22%	9.27%
Common equity tier 1 capital	$ 1,029,763	$ 879,424
Common equity tier 1 capital minimum capital requirements, ratio	5.75%	5.125%
Tier 1 Risk-based Capital
Tier 1 risk-based capital actual, amount	$ 1,864,279	$ 1,698,767
Tier 1 risk-based capital actual, ratio	10.41%	9.90%
Tier 1 risk-based capital minimum capital requirements, amount	$ 1,298,397	$ 1,136,816
Tier 1 risk-based capital minimum capital requirements, ratio	7.25%	6.625%
Tier 1 Leverage Capital
Tier 1 leverage capital actual, amount	$ 1,864,279	$ 1,698,767
Tier 1 leverage capital actual, ratio	8.03%	7.74%
Tier 1 leverage capital minimum capital requirements, amount	$ 928,484	$ 878,244
Tier 1 leverage capital minimum capital requirements, ratio	4.00%	4.00%
Valley National Bank
Total Risk-based Capital
Risk-based capital actual, amount	$ 2,185,967	$ 2,023,857
Risk-based capital actual, ratio	12.23%	11.82%
Risk-based capital minimum capital requirements, amount	$ 1,653,088	$ 1,476,767
Risk-based capital minimum capital requirements, ratio	9.25%	8.625%
Risk-based capital to be well capitalized under prompt corrective action provision, amount	$ 1,787,122	$ 1,712,193
Risk-based capital to be well capitalized under prompt corrective action provision, ratio	10.00%	10.00%
Common Equity Tier 1 Capital
Common equity tier 1 capital, amount	$ 1,961,316	$ 1,807,201
Common equity tier 1 capital, ratio	10.97%	10.55%
Common equity tier 1 capital	$ 1,027,595	$ 877,499
Common equity tier 1 capital minimum capital requirements, ratio	5.75%	5.125%
Common equity tier 1 capital to be well capitalized under prompt corrective action provision, amount	$ 1,161,629	$ 1,112,926
Common equity tier 1 capital to be well capitalized under prompt corrective action provision, ratio	6.50%	6.50%
Tier 1 Risk-based Capital
Tier 1 risk-based capital actual, amount	$ 1,961,316	$ 1,807,201
Tier 1 risk-based capital actual, ratio	10.97%	10.55%
Tier 1 risk-based capital minimum capital requirements, amount	$ 1,295,663	$ 1,134,328
Tier 1 risk-based capital minimum capital requirements, ratio	7.25%	6.625%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provision, amount	$ 1,429,698	$ 1,369,755
Tier 1 risk-based capital to be well capitalized under prompt corrective action provision, ratio	8.00%	8.00%
Tier 1 Leverage Capital
Tier 1 leverage capital actual, amount	$ 1,961,316	$ 1,807,201
Tier 1 leverage capital actual, ratio	8.47%	8.25%
Tier 1 leverage capital minimum capital requirements, amount	$ 926,459	$ 876,026
Tier 1 leverage capital minimum capital requirements, ratio	4.00%	4.00%
Tier 1 leverage capital to be well capitalized under prompt corrective action provision, amount	$ 1,158,074	$ 1,095,032
Tier 1 leverage capital to be well capitalized under prompt corrective action provision, ratio	5.00%	5.00%