Shareholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2015

Sep. 30, 2015

Jun. 30, 2015

Mar. 31, 2015

Dec. 31, 2014

Sep. 30, 2014

Dec. 31, 2015

Dec. 31, 2014

Equity [Abstract]

Dividend declared

$ 484

$ 181

Dividends per share

$ 0.02

$ 0.01

$ 0.08

$ 0.03

Regulatory capital, description

The FDIC issued a notice of proposed rulemaking in June 2015 that it revised in January 2016 to set forth several significant proposed changes to the methodology for calculating deposit insurance assessments for banks with less than $10 billion in assets. Under the proposed rule, the current system would be eliminated, and the rate would instead be determined based on a number of factors, including the bank’s CAMELS ratings, leverage ratio, net income, non-performing loan ratios, OREO ratios, core deposit ratios, one-year organic asset growth and a loan mix index. The CAMELS rating system is a supervisory rating system developed to classify a bank’s overall condition by taking into account capital adequacy, assets, management capability, earnings, liquidity and sensitivity to market and interest rate risk. The loan mix index component of the assessment model requires banks to calculate each of their loan categories as a percentage of assets and then multiply each category by a standardized historical charge-off rate percentage provided by the FDIC, with a higher index leading to a higher assessment rate. The proposal would implement maximum assessment rates for institutions with a composite CAMELS rating of 1 or 2 and minimum rates for institutions with a rating of 3, 4 or 5. As revised, the rules would go into effect the quarter after the reserve ratio of the Deposit Insurance Fund reaches 1.15 percent (or the first quarter after a final rule is adopted that the rule can take effect, whichever is later).

Dividend restrictions, description

Under applicable Delaware law, dividends may be paid only out of “surplus,” defined as an amount equal to the present fair value of the total assets of the corporation, minus the present fair value of the total liabilities of the corporation, minus the capital of the corporation as determined in accordance with the Delaware General Corporation Law. In the event that there is no surplus, dividends may be paid out of the net profits of the corporation for the fiscal year in which the dividend is declared and/or the immediately preceding fiscal year. Dividends may not be paid, however, out of net profits of the corporation if the capital represented by the issued and outstanding stock of all classes having a preference on the distribution of assets is impaired. Further, it is the policy of the Federal Reserve that bank holding companies should pay dividends only out of current earnings and only if future retained earnings would be consistent with the company’s capital, asset quality and financial condition. Since it has no significant independent sources of income, USBI’s ability to pay dividends depends on its ability to receive dividends from the Bank. Under Alabama law, a state-chartered bank must annually transfer to surplus at least 10% of its “net earnings” (defined as the remainder of all earnings from current operations plus actual recoveries on loans and investments and other assets, less all current operating expenses, actual losses, accrued dividends on preferred stock, and all federal, state and local taxes) until the bank’s surplus is at least 20% of its capital. Until the bank’s surplus reaches this level, a bank may not declare a dividend in excess of 90% of its net earnings. Once a bank’s surplus equals or exceeds 20% of its capital, if the total of all dividends declared by the bank in a calendar year will exceed the sum of its net earnings for that year and its retained net earnings for the preceding two years (less any required transfers to surplus), then the bank must obtain prior written approval from the Superintendent of the Alabama State Banking Department. The bank may not pay any dividends or make any withdrawals or transfers from surplus without the prior written approval of the Superintendent. The FDIC prohibits the payment of cash dividends if (i) as a result of such payment, the bank would be undercapitalized or (ii) the bank is in default with respect to any assessment due to the FDIC, including a deposit insurance assessment. These restrictions could materially influence the Bank’s, and therefore USBI’s, ability to pay dividends.