Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Tax Cuts and Jobs Act of 2017, change in tax rate, deferred tax asset, income tax expense (benefit)	$ 1,300,000
Excise tax on real estate investment trust (REIT) dividend	1,945,000	$ 0	$ 0
Effective income tax rate reconciliation, change in enacted tax rate and excise tax on real estate investment trust dividend, amount	$ 602,000
Statutory federal rate	35.00%
Net deferred tax assets	$ 2,857,000	17,910,000
Pascack Bancorp, Inc.
Income Tax Disclosure [Line Items]
Net deferred tax assets		4,400,000
Harmony Bank
Income Tax Disclosure [Line Items]
Net deferred tax liabilities		$ (164,000)