Regulatory and Capital Requirements - Schedule of Actual Capital Positions and Ratios under Banking Regulations (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Total Risk-based Capital
Risk-based capital actual, amount	$ 3,427,134	$ 2,786,971
Risk-based capital actual, ratio	11.72%	11.34%
Risk-based capital minimum capital requirements, amount	$ 3,070,687	$ 2,426,975
Risk-based capital minimum capital requirements, ratio	10.50%	9.875%
Common Equity Tier 1 Capital
Common equity tier 1 capital, amount	$ 2,754,524	$ 2,071,871
Common equity tier 1 capital, ratio	9.42%	8.43%
Common equity tier 1 capital	$ 2,047,125	$ 1,566,781
Common equity tier 1 capital minimum capital requirements, ratio	7.00%	6.375%
Tier 1 Risk-based Capital
Tier 1 risk-based capital actual, amount	$ 2,968,530	$ 2,286,676
Tier 1 risk-based capital actual, ratio	10.15%	9.30%
Tier 1 risk-based capital minimum capital requirements, amount	$ 2,485,795	$ 1,935,435
Tier 1 risk-based capital minimum capital requirements, ratio	8.50%	7.875%
Tier 1 Leverage Capital
Tier 1 leverage capital actual, amount	$ 2,968,530	$ 2,286,676
Tier 1 leverage capital actual, ratio	8.76%	7.57%
Tier 1 leverage capital minimum capital requirements, amount	$ 1,355,378	$ 1,208,882
Tier 1 leverage capital minimum capital requirements, ratio	4.00%	4.00%
Valley National Bank
Total Risk-based Capital
Risk-based capital actual, amount	$ 3,416,674	$ 2,698,654
Risk-based capital actual, ratio	11.69%	10.99%
Risk-based capital minimum capital requirements, amount	$ 3,069,894	$ 2,424,059
Risk-based capital minimum capital requirements, ratio	10.50%	9.875%
Risk-based capital to be well capitalized under prompt corrective action provision, amount	$ 2,923,709	$ 2,454,743
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	$ 3,152,070	$ 2,442,359
Common equity tier 1 capital, ratio	10.78%	9.95%
Common equity tier 1 capital	$ 2,046,596	$ 1,564,899
Common equity tier 1 capital minimum capital requirements, ratio	7.00%	6.375%
Common equity tier 1 capital to be well capitalized under prompt corrective action provision, amount	$ 1,900,411	$ 1,595,583
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	$ 3,152,070	$ 2,442,359
Tier 1 risk-based capital actual, ratio	10.78%	9.95%
Tier 1 risk-based capital minimum capital requirements, amount	$ 2,485,153	$ 1,933,110
Tier 1 risk-based capital minimum capital requirements, ratio	8.50%	7.875%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provision, amount	$ 2,338,967	$ 1,963,794
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	$ 3,152,070	$ 2,442,359
Tier 1 leverage capital actual, ratio	9.31%	8.09%
Tier 1 leverage capital minimum capital requirements, amount	$ 1,354,693	$ 1,207,039
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	$ 1,693,366	$ 1,508,798
Tier 1 leverage capital to be well capitalized under prompt corrective action provision, ratio	5.00%	5.00%