Subsequent Event (Detail Textuals) - Tidelands Bancshares Inc $ / shares in Units, $ in Thousands	6 Months Ended
Jun. 30, 2016 USD ($) Branch $ / shares
Subsequent Event [Line Items]
Total assets	$ 446,000
Loans	321,000
Deposits	$ 398,000
Number of branches \| Branch	7
Cash price per share \| $ / shares	$ 0.52
Cash payment for acquisition	$ 2,220
Unpaid dividends	$ 8,980
Discount rate	56.00%

Represents amount of deposit recognized as of the acquisition date.

No definition available.

Name:	ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeposits
Namespace Prefix:	ucbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents amount of loans net recognized as of the acquisition date.

+ References

No definition available.

+ Details

Name:	ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansNet
Namespace Prefix:	ucbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents percentage of discount rate.

+ References

No definition available.

+ Details

Name:	ucbi_DiscountRate
Namespace Prefix:	ucbi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents number of branches operated by entity.

+ References

No definition available.

+ Details

Name:	ucbi_NumberOfBranches
Namespace Prefix:	ucbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents amount of preferred stock and accrued dividends.

+ References

No definition available.

+ Details

Name:	ucbi_PreferredStockAndAccruedDividends
Namespace Prefix:	ucbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessAcquisitionSharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of assets acquired at the acquisition date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=73530397&loc=d3e4845-128472

+ Details

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=ucbi_TidelandsBancsharesIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: