Other Real Estate Owned - Additional Information (Detail)	12 Months Ended
Dec. 31, 2014
Real Estate [Abstract]
Maximum period for recording the adjustments to loan losses	60 days

Maximum period for recording the adjustments to loan losses.

No definition available.

Name:	usbi_MaximumPeriodForRecordingAdjustmentsToLoanLosses
Namespace Prefix:	usbi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration