Regulatory and Capital Requirements - Schedule of Actual Capital Positions and Ratios under Banking Regulations (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Total Risk-based Capital
Risk-based capital actual, amount	$ 2,786,971	$ 2,258,044
Risk-based capital actual, ratio	11.34%	12.61%
Risk-based capital minimum capital requirements, amount	$ 2,426,975	$ 1,656,575
Risk-based capital minimum capital requirements, ratio	9.875%	9.25%
Common Equity Tier 1 Capital
Common equity tier 1 capital, amount	$ 2,071,871	$ 1,651,849
Common equity tier 1 capital, ratio	8.43%	9.22%
Common equity tier 1 capital	$ 1,566,781	$ 1,029,763
Common equity tier 1 capital minimum capital requirements, ratio	6.375%	5.75%
Tier 1 Risk-based Capital
Tier 1 risk-based capital actual, amount	$ 2,286,676	$ 1,864,279
Tier 1 risk-based capital actual, ratio	9.30%	10.41%
Tier 1 risk-based capital minimum capital requirements, amount	$ 1,935,435	$ 1,298,397
Tier 1 risk-based capital minimum capital requirements, ratio	7.875%	7.25%
Tier 1 Leverage Capital
Tier 1 leverage capital actual, amount	$ 2,286,676	$ 1,864,279
Tier 1 leverage capital actual, ratio	7.57%	8.03%
Tier 1 leverage capital minimum capital requirements, amount	$ 1,208,882	$ 928,484
Tier 1 leverage capital minimum capital requirements, ratio	4.00%	4.00%
Valley National Bank
Total Risk-based Capital
Risk-based capital actual, amount	$ 2,698,654	$ 2,185,967
Risk-based capital actual, ratio	10.99%	12.23%
Risk-based capital minimum capital requirements, amount	$ 2,424,059	$ 1,653,088
Risk-based capital minimum capital requirements, ratio	9.875%	9.25%
Risk-based capital to be well capitalized under prompt corrective action provision, amount	$ 2,454,743	$ 1,787,122
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	$ 2,442,359	$ 1,961,316
Common equity tier 1 capital, ratio	9.95%	10.97%
Common equity tier 1 capital	$ 1,564,899	$ 1,027,595
Common equity tier 1 capital minimum capital requirements, ratio	6.375%	5.75%
Common equity tier 1 capital to be well capitalized under prompt corrective action provision, amount	$ 1,595,583	$ 1,161,629
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	$ 2,442,359	$ 1,961,316
Tier 1 risk-based capital actual, ratio	9.95%	10.97%
Tier 1 risk-based capital minimum capital requirements, amount	$ 1,933,110	$ 1,295,663
Tier 1 risk-based capital minimum capital requirements, ratio	7.875%	7.25%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provision, amount	$ 1,963,794	$ 1,429,698
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	$ 2,442,359	$ 1,961,316
Tier 1 leverage capital actual, ratio	8.09%	8.47%
Tier 1 leverage capital minimum capital requirements, amount	$ 1,207,039	$ 926,459
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	$ 1,508,798	$ 1,158,074
Tier 1 leverage capital to be well capitalized under prompt corrective action provision, ratio	5.00%	5.00%