Condensed Financial Statements of United Community Banks, Inc. (Holding Company Only) - Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities:
Net income	$ 277,472	$ 269,801	$ 164,089
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation	8,705	6,554	7,887
Changes in assets and liabilities:
Other assets	(14,694)	53,416	(20,139)
Net cash provided by operating activities	607,307	359,320	158,681
Investing activities:
Net cash (paid) received for acquisition	35,243	103,065	195,699
Other investing inflows	3,189	767	5,241
Other investing outflows	0	(610)	0
Net cash (used in) provided by investing activities	(2,020,181)	(1,806,403)	(1,580,563)
Financing activities:
Proceeds from issuance of preferred stock, net of issuance costs	0	0	96,422
Repurchase of common stock	0	(15,101)	(20,782)
Cash dividends on preferred stock	(6,875)	(6,876)	(3,533)
Cash dividends on common stock	(86,883)	(66,914)	(58,912)
Other financing outflows	(8,154)	(3,182)	(3,119)
Net cash (used in) provided by financing activities	(258,783)	2,156,974	2,515,295
Net change in cash and cash equivalents	(1,671,657)	709,891	1,093,413
Cash and cash equivalents at beginning of year	2,318,510	1,608,619	515,206
Cash and cash equivalents at end of year	646,853	2,318,510	1,608,619
Holding Company
Operating activities:
Net income	277,472	269,801	164,089
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of the subsidiaries	(157,152)	(61,065)	(27,419)
Stock-based compensation	8,705	6,554	7,887
Changes in assets and liabilities:
Other assets	6,094	(7,800)	(3,662)
Other liabilities	7,736	6,353	5,261
Net cash provided by operating activities	142,855	213,843	146,156
Investing activities:
Net cash (paid) received for acquisition	(47)	(47,785)	3,397
Purchases of debt securities available-for-sale and equity securities with readily determinable fair values	(19,060)	(1,500)	(2,750)
Proceeds from sales and maturities of debt securities available-for-sale and equity securities with readily determinable fair values	4,473	1,253	0
Other investing inflows	19	860	0
Other investing outflows	(3,676)	(630)	0
Net cash (used in) provided by investing activities	(18,291)	(47,802)	647
Financing activities:
Repayment of long-term debt	0	(65,632)	0
Proceeds from issuance of long-term debt, net of issuance costs	0	0	98,552
Proceeds from issuance of preferred stock, net of issuance costs	0	0	96,422
Cash paid for shares withheld to cover payroll taxes related to equity instruments	(3,494)	(3,182)	(3,119)
Proceeds from issuance of common stock for dividend reinvestment and employee benefit plans	301	506	1,317
Proceeds from exercise of options and warrants	824	231	0
Repurchase of common stock	0	(15,101)	(20,782)
Cash dividends on preferred stock	6,875	6,876	3,533
Cash dividends on common stock	(86,883)	(66,914)	(58,912)
Other financing outflows	(4,400)	0	0
Net cash (used in) provided by financing activities	(100,527)	(156,968)	109,945
Net change in cash and cash equivalents	24,037	9,073	256,748
Cash and cash equivalents at beginning of year	298,316	289,243	32,495
Cash and cash equivalents at end of year	$ 322,353	$ 298,316	$ 289,243