Loans, Net - Summary of Activity Pertaining to Allowance for Loan Losses (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 12,089	$ 11,132	$ 9,987
Charge-offs	(2,978)	(2,364)	(2,392)
Recoveries	210	182	295
Provision (credit)	4,092	3,139	3,242
Ending balance	13,413	12,089	11,132
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,680	3,446	2,801
Charge-offs	(839)	(637)	(1,556)
Recoveries	25	125	235
Provision (credit)	1,189	(254)	1,966
Ending balance	3,055	2,680	3,446
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	5,497	5,572	5,000
Charge-offs	(1,349)	(870)	(589)
Recoveries	90	45	52
Provision (credit)	2,070	750	1,109
Ending balance	6,308	5,497	5,572
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	710	860	668
Charge-offs		(127)	(78)
Recoveries		1	3
Provision (credit)	385	(24)	267
Ending balance	1,095	710	860
Business Banking Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	788
Charge-offs	(123)	(128)
Recoveries		2
Provision (credit)	(11)	914
Ending balance	654	788
Business Banking Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	706
Charge-offs	(122)	(52)
Recoveries
Provision (credit)	(51)	758
Ending balance	533	706
Residential Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	602	666	740
Charge-offs	(389)	(246)	(139)
Recoveries	60
Provision (credit)	532	182	65
Ending balance	805	602	666
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	383	474	623
Charge-offs	(89)	(225)	(24)
Recoveries	6
Provision (credit)	74	134	(125)
Ending balance	374	383	474
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	83	114	155
Charge-offs	(67)	(79)	(6)
Recoveries	29	9	5
Provision (credit)	18	39	(40)
Ending balance	63	83	114
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	640
Charge-offs
Recoveries
Provision (credit)	(114)	640
Ending balance	$ 526	$ 640

United Financial Bancorp, Inc. 10-K