BUSINESS COMBINATIONS - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ / shares in Units, $ in Thousands						12 Months Ended
	Jul. 01, 2019	Jun. 29, 2018	May 25, 2018	Jan. 31, 2018	Jan. 03, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 31, 2018
Deposits:
Goodwill						$ 928,005	$ 931,637	$ 503,434
Consideration:
Issuance of common stock in acquisitions						0	$ 869,294	$ 547,127
Fidelity Southern Corporation
Assets
Cash and due from banks						23,847
Federal funds sold and interest-bearing deposits in banks						217,936
Investment securities						297,897
Other investments						7,449
Loans held for sale						327,617
Loans	$ 3,510,000					3,512,262
Less allowance for loan losses						0
Loans, net						3,512,262
Other real estate owned						7,178
Premises and equipment						101,249
Other intangible assets, net						50,610
Cash value of bank owned life insurance						72,328
Deferred income taxes, net						0
Other assets						141,723
Total assets						4,760,096
Deposits:
Noninterest-bearing						1,299,715
Interest-bearing						2,741,494
Total deposits						4,041,209
Securities sold under agreements to repurchase						22,345
Other borrowings						151,332
Subordinated deferrable interest debenture						36,718
Deferred tax liability						1,318
Other liabilities						64,726
Total liabilities						4,317,648
Net identifiable assets acquired over (under) liabilities assumed						442,448
Goodwill						426,865
Net assets acquired over liabilities assumed						869,313
Consideration:
Ameris Bancorp common shares issued (in shares)	22,181,522
Share price (in dollars per share)	$ 39.19
Company common stock issued	$ 869,294
Issuance of common stock in acquisitions	869,300
Cash exchanged for shares	19
Fair value of total consideration transferred	869,313
Fidelity Southern Corporation | Initial Fair Value Adjustments
Assets
Cash and due from banks	0
Federal funds sold and interest-bearing deposits in banks	0
Investment securities	(1,444)
Other investments	0
Loans held for sale	(1,290)
Loans	(79,002)
Less allowance for loan losses	31,245
Loans, net	(47,757)
Other real estate owned	(427)
Premises and equipment	11,407
Other intangible assets, net	39,940
Cash value of bank owned life insurance	0
Deferred income taxes, net	(104)
Other assets	998
Total assets	1,323
Deposits:
Noninterest-bearing	0
Interest-bearing	942
Total deposits	942
Securities sold under agreements to repurchase	0
Other borrowings	2,265
Subordinated deferrable interest debenture	(9,675)
Deferred tax liability	(11,401)
Other liabilities	538
Total liabilities	(17,331)
Net identifiable assets acquired over (under) liabilities assumed	18,654
Goodwill	410,348
Net assets acquired over liabilities assumed	429,002
Fidelity Southern Corporation | Subsequent Adjustments
Assets
Cash and due from banks	(2,417)
Federal funds sold and interest-bearing deposits in banks	0
Investment securities	0
Other investments	0
Loans held for sale	250
Loans	3,852
Less allowance for loan losses	0
Loans, net	3,852
Other real estate owned	0
Premises and equipment	(3,820)
Other intangible assets, net	0
Cash value of bank owned life insurance	0
Deferred income taxes, net	0
Other assets	(17,138)
Total assets	(19,273)
Deposits:
Noninterest-bearing	(2,114)
Interest-bearing	0
Total deposits	(2,114)
Securities sold under agreements to repurchase	0
Other borrowings	(300)
Subordinated deferrable interest debenture	0
Deferred tax liability	497
Other liabilities	(839)
Total liabilities	(2,756)
Net identifiable assets acquired over (under) liabilities assumed	(16,517)
Goodwill	16,517
Net assets acquired over liabilities assumed	0
Hamilton State Bancshares, Inc.
Assets
Cash and due from banks						13,927
Federal funds sold and interest-bearing deposits in banks						102,156
Time deposits in other banks						11,558
Investment securities						285,830
Other investments						2,094
Loans		$ 1,290,000				1,293,186
Less allowance for loan losses						0
Loans, net						1,293,186
Other real estate owned						847
Premises and equipment						28,971
Other intangible assets, net						23,610
Cash value of bank owned life insurance						4,454
Deferred income taxes, net						10,079
Other assets						10,955
Total assets						1,787,667
Deposits:
Noninterest-bearing						381,039
Interest-bearing						1,204,211
Total deposits						1,585,250
Other borrowings						10,907
Subordinated deferrable interest debenture						2,292
Other liabilities						12,851
Total liabilities						1,611,300
Net identifiable assets acquired over (under) liabilities assumed						176,367
Goodwill						220,768
Net assets acquired over liabilities assumed						397,135
Consideration:
Ameris Bancorp common shares issued (in shares)		6,548,385
Share price (in dollars per share)		$ 53.35
Company common stock issued		$ 349,400
Issuance of common stock in acquisitions		349,356
Cash exchanged for shares		47,779
Fair value of total consideration transferred		397,135
Hamilton State Bancshares, Inc. | Initial Fair Value Adjustments
Assets
Cash and due from banks		0
Federal funds sold and interest-bearing deposits in banks		0
Time deposits in other banks		0
Investment securities		(2,376)
Other investments		0
Loans		(15,528)
Less allowance for loan losses		11,183
Loans, net		(4,345)
Other real estate owned		0
Premises and equipment		0
Other intangible assets, net		(2,755)
Cash value of bank owned life insurance		0
Deferred income taxes, net		(6,308)
Other assets		0
Total assets		(15,784)
Deposits:
Noninterest-bearing		0
Interest-bearing		(1,896)
Total deposits		(1,896)
Other borrowings		(66)
Subordinated deferrable interest debenture		(658)
Other liabilities		2,391
Total liabilities		(229)
Net identifiable assets acquired over (under) liabilities assumed		(15,555)
Goodwill		220,713
Net assets acquired over liabilities assumed		205,158
Hamilton State Bancshares, Inc. | Subsequent Adjustments
Assets
Cash and due from banks						(478)
Federal funds sold and interest-bearing deposits in banks						0
Time deposits in other banks						0
Investment securities						0
Other investments						0
Loans						(5,550)
Less allowance for loan losses						0
Loans, net						(5,550)
Other real estate owned						0
Premises and equipment						1,488
Other intangible assets, net						7,610
Cash value of bank owned life insurance						0
Deferred income taxes, net						3,942
Other assets						(2,098)
Total assets						4,914
Deposits:
Noninterest-bearing						0
Interest-bearing						4,783
Total deposits						4,783
Other borrowings						286
Subordinated deferrable interest debenture						(143)
Other liabilities						0
Total liabilities						4,926
Net identifiable assets acquired over (under) liabilities assumed						(12)
Goodwill						55
Net assets acquired over liabilities assumed						43
Atlantic Coast Financial Corporation
Assets
Cash and due from banks						3,990
Federal funds sold and interest-bearing deposits in banks						22,149
Investment securities						35,126
Other investments						9,576
Loans held for sale						358
Loans			$ 755,700			755,704
Less allowance for loan losses						0
Loans, net						755,704
Other real estate owned						1,041
Premises and equipment						10,735
Other intangible assets, net						7,488
Cash value of bank owned life insurance						18,182
Deferred income taxes, net						7,711
Other assets						2,959
Total assets						875,019
Deposits:
Noninterest-bearing						69,761
Interest-bearing						515,406
Total deposits						585,167
Other borrowings						204,475
Other liabilities						6,432
Total liabilities						796,074
Net identifiable assets acquired over (under) liabilities assumed						78,945
Goodwill						90,342
Net assets acquired over liabilities assumed						169,287
Consideration:
Ameris Bancorp common shares issued (in shares)			2,631,520
Share price (in dollars per share)			$ 56.15
Company common stock issued			$ 147,760
Cash exchanged for shares			21,527
Fair value of total consideration transferred			169,287
Atlantic Coast Financial Corporation | Initial Fair Value Adjustments
Assets
Cash and due from banks			0
Federal funds sold and interest-bearing deposits in banks			0
Investment securities			(60)
Other investments			0
Loans held for sale			0
Loans			(19,423)
Less allowance for loan losses			8,573
Loans, net			(10,850)
Other real estate owned			(796)
Premises and equipment			(1,695)
Other intangible assets, net			5,937
Cash value of bank owned life insurance			0
Deferred income taxes, net			709
Other assets			(634)
Total assets			(7,389)
Deposits:
Noninterest-bearing			0
Interest-bearing			(554)
Total deposits			(554)
Other borrowings			0
Other liabilities			(13)
Total liabilities			(567)
Net identifiable assets acquired over (under) liabilities assumed			(6,822)
Goodwill			91,360
Net assets acquired over liabilities assumed			84,538
Atlantic Coast Financial Corporation | Subsequent Adjustments
Assets
Cash and due from banks						0
Federal funds sold and interest-bearing deposits in banks						0
Investment securities						0
Other investments						0
Loans held for sale						0
Loans						(2,478)
Less allowance for loan losses						0
Loans, net						(2,478)
Other real estate owned						0
Premises and equipment						(161)
Other intangible assets, net						1,551
Cash value of bank owned life insurance						0
Deferred income taxes, net						1,220
Other assets						(11)
Total assets						121
Deposits:
Noninterest-bearing						0
Interest-bearing						1,025
Total deposits						1,025
Other borrowings						0
Other liabilities						(1,922)
Total liabilities						(897)
Net identifiable assets acquired over (under) liabilities assumed						1,018
Goodwill						(1,018)
Net assets acquired over liabilities assumed						0
US Premium Financing Holding Company
Assets
Total assets						23,607
Deposits:
Deferred tax liability						5,124
Total liabilities						5,124
Net identifiable assets acquired over (under) liabilities assumed						18,483
Goodwill						64,498
Net assets acquired over liabilities assumed						82,981
Consideration:
Ameris Bancorp common shares issued (in shares)				830,301					1,073,158
Share price (in dollars per share)				$ 53.55					$ 53.55
Company common stock issued				$ 44,500	$ 5,500
Issuance of common stock in acquisitions									$ 55,855
Cash exchanged for shares									21,421
Present value of contingent earn-out consideration expected to be paid									5,705
Fair value of total consideration transferred				8,900	$ 12,500				82,981
US Premium Financing Holding Company | Initial Fair Value Adjustments
Assets
Total assets				21,314					21,314
Deposits:
Deferred tax liability				5,492					5,492
Total liabilities				5,492					5,492
Net identifiable assets acquired over (under) liabilities assumed				15,822					15,822
Goodwill				67,159					67,159
Net assets acquired over liabilities assumed				82,981					82,981
US Premium Financing Holding Company | Subsequent Adjustments
Assets
Total assets						2,293
Deposits:
Deferred tax liability						(368)
Total liabilities						(368)
Net identifiable assets acquired over (under) liabilities assumed						2,661
Goodwill						(2,661)
Net assets acquired over liabilities assumed						0
As Previously Reported | Fidelity Southern Corporation
Assets
Cash and due from banks	26,264
Federal funds sold and interest-bearing deposits in banks	217,936
Investment securities	299,341
Other investments	7,449
Loans held for sale	328,657
Loans	3,587,412
Less allowance for loan losses	(31,245)
Loans, net	3,556,167
Other real estate owned	7,605
Premises and equipment	93,662
Other intangible assets, net	10,670
Cash value of bank owned life insurance	72,328
Deferred income taxes, net	104
Other assets	157,863
Total assets	4,778,046
Deposits:
Noninterest-bearing	1,301,829
Interest-bearing	2,740,552
Total deposits	4,042,381
Securities sold under agreements to repurchase	22,345
Other borrowings	149,367
Subordinated deferrable interest debenture	46,393
Deferred tax liability	12,222
Other liabilities	65,027
Total liabilities	4,337,735
Net identifiable assets acquired over (under) liabilities assumed	440,311
Goodwill	0
Net assets acquired over liabilities assumed	$ 440,311
As Previously Reported | Hamilton State Bancshares, Inc.
Assets
Cash and due from banks		14,405
Federal funds sold and interest-bearing deposits in banks		102,156
Time deposits in other banks		11,558
Investment securities		288,206
Other investments		2,094
Loans		1,314,264
Less allowance for loan losses		(11,183)
Loans, net		1,303,081
Other real estate owned		847
Premises and equipment		27,483
Other intangible assets, net		18,755
Cash value of bank owned life insurance		4,454
Deferred income taxes, net		12,445
Other assets		13,053
Total assets		1,798,537
Deposits:
Noninterest-bearing		381,039
Interest-bearing		1,201,324
Total deposits		1,582,363
Other borrowings		10,687
Subordinated deferrable interest debenture		3,093
Other liabilities		10,460
Total liabilities		1,606,603
Net identifiable assets acquired over (under) liabilities assumed		191,934
Goodwill		0
Net assets acquired over liabilities assumed		$ 191,934
As Previously Reported | Atlantic Coast Financial Corporation
Assets
Cash and due from banks			3,990
Federal funds sold and interest-bearing deposits in banks			22,149
Investment securities			35,186
Other investments			9,576
Loans held for sale			358
Loans			777,605
Less allowance for loan losses			(8,573)
Loans, net			769,032
Other real estate owned			1,837
Premises and equipment			12,591
Other intangible assets, net			0
Cash value of bank owned life insurance			18,182
Deferred income taxes, net			5,782
Other assets			3,604
Total assets			882,287
Deposits:
Noninterest-bearing			69,761
Interest-bearing			514,935
Total deposits			584,696
Other borrowings			204,475
Other liabilities			8,367
Total liabilities			797,538
Net identifiable assets acquired over (under) liabilities assumed			84,749
Goodwill			0
Net assets acquired over liabilities assumed			$ 84,749
As Previously Reported | US Premium Financing Holding Company
Assets
Total assets				0					0
Deposits:
Deferred tax liability				0					0
Total liabilities				0					0
Net identifiable assets acquired over (under) liabilities assumed				0					0
Goodwill				0					0
Net assets acquired over liabilities assumed				0					0
Insurance agent relationships | US Premium Financing Holding Company
Assets
Other intangible assets, net						22,351
Insurance agent relationships | US Premium Financing Holding Company | Initial Fair Value Adjustments
Assets
Other intangible assets, net				20,000					20,000
Insurance agent relationships | US Premium Financing Holding Company | Subsequent Adjustments
Assets
Other intangible assets, net						2,351
Insurance agent relationships | As Previously Reported | US Premium Financing Holding Company
Assets
Other intangible assets, net				0					0
US Premium Finance trade name | US Premium Financing Holding Company
Assets
Other intangible assets, net						1,094
US Premium Finance trade name | US Premium Financing Holding Company | Initial Fair Value Adjustments
Assets
Other intangible assets, net				1,136					1,136
US Premium Finance trade name | US Premium Financing Holding Company | Subsequent Adjustments
Assets
Other intangible assets, net						(42)
US Premium Finance trade name | As Previously Reported | US Premium Financing Holding Company
Assets
Other intangible assets, net				0					0
Non-compete agreement | US Premium Financing Holding Company
Assets
Other intangible assets, net						162
Non-compete agreement | US Premium Financing Holding Company | Initial Fair Value Adjustments
Assets
Other intangible assets, net				178					178
Non-compete agreement | US Premium Financing Holding Company | Subsequent Adjustments
Assets
Other intangible assets, net						$ (16)
Non-compete agreement | As Previously Reported | US Premium Financing Holding Company
Assets
Other intangible assets, net				$ 0					$ 0
Weighted Average | US Premium Financing Holding Company
Consideration:
Share price (in dollars per share)				$ 52.047					$ 52.047