Regulatory Capital Matters - Components of Regulatory Capital (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total shareholders' equity	$ 294,265	$ 249,806	$ 244,245	$ 240,135
Accumulated other comprehensive loss	(18,685)	(21,040)
United Community [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total shareholders' equity	294,265	249,806
Accumulated other comprehensive loss	18,701	21,040
Intangible assets	(23,416)	(1,567)
Disallowed deferred tax assets	(3,806)	(10,410)
Tier 1 Capital	285,744	258,869
Allowance for loan losses and allowance for unfunded lending commitments limited to 1.25% of total risk-weighted assets	21,202	18,948
Total risk-based capital	306,946	277,817
Home Savings [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total shareholders' equity	276,494	216,475
Accumulated other comprehensive loss	18,701	21,056
Intangible assets	(20,903)	(3)
Disallowed deferred tax assets	(2,515)	(7,590)
Tier 1 Capital	271,777	229,938
Allowance for loan losses and allowance for unfunded lending commitments limited to 1.25% of total risk-weighted assets	21,151	18,923
Total risk-based capital	$ 292,928	$ 248,861