BUSINESS COMBINATIONS - Schedule of Assets And Liabilities Acquired (Details) - USD ($) $ / shares in Units, $ in Thousands						1 Months Ended	9 Months Ended		12 Months Ended
	Jul. 01, 2019	Jun. 29, 2018	May 25, 2018	Jan. 31, 2018	Jan. 03, 2018	Jan. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 31, 2018	Jun. 30, 2019	Dec. 31, 2018
Liabilities
Goodwill							$ 911,488	$ 505,604			$ 503,434
Company common stock issued							869,294	$ 547,127
Fidelity Southern Corporation
Assets
Cash and due from banks							26,264
Federal funds sold and interest-bearing deposits in banks							217,936
Investment securities							297,897
Other investments							7,449
Loans held for sale							327,367
Loans	$ 3,510,000						3,508,410
Less allowance for loan losses							0
Loans, net							3,508,410
Other real estate owned							7,178
Premises and equipment							105,069
Other intangible assets, net							50,610
Cash value of bank owned life insurance							72,328
Deferred income taxes, net							0
Other assets							158,861
Total assets							4,779,369
Liabilities
Noninterest-bearing							1,301,829
Interest-bearing							2,741,494
Total deposits							4,043,323
Securities sold under agreements to repurchase							22,345
Other borrowings							151,632
Subordinated deferrable interest debenture							36,718
Deferred tax liability							821
Other liabilities							65,565
Total liabilities							4,320,404
Net identifiable assets acquired over (under) liabilities assumed							458,965
Goodwill	$ 410,300						410,348
Net assets acquired over liabilities assumed							$ 869,313
Ameris Bancorp common shares issued (in shares)	22,181,522
Price per share of the Company's common stock (in dollars per share)	$ 39.19
Company common stock issued	$ 869,294
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
Liabilities
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
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
Liabilities
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		$ 220,800								220,768
Net assets acquired over liabilities assumed										397,135
Ameris Bancorp common shares issued (in shares)		6,548,385
Price per share of the Company's common stock (in dollars per share)		$ 53.35
Company common stock issued		$ 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)
Liabilities
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
Liabilities
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
Liabilities
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			$ 90,300							90,342
Net assets acquired over liabilities assumed										169,287
Ameris Bancorp common shares issued (in shares)			2,631,520
Price per share of the Company's common stock (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)
Liabilities
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
Liabilities
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		$ 23,607			$ 23,607
Liabilities
Deferred tax liability				5,124		5,124			5,124
Total liabilities				5,124		5,124			5,124
Net identifiable assets acquired over (under) liabilities assumed				18,483		18,483			18,483
Goodwill				64,498		64,498			64,498
Net assets acquired over liabilities assumed				$ 82,981		$ 82,981			$ 82,981
Ameris Bancorp common shares issued (in shares)				830,301		1,073,158			1,073,158
Price per share of the Company's common stock (in dollars per share)				$ 53.55		$ 53.55			$ 53.55
Company common stock issued						$ 55,900			$ 55,855
Cash exchanged for shares						21,400			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 | Insurance Agent Relationships
Assets
Other intangible assets, net				22,351		22,351			22,351
US Premium Financing Holding Company | Trade Names
Assets
Other intangible assets, net				1,094		1,094			1,094
US Premium Financing Holding Company | Noncompete Agreements
Assets
Other intangible assets, net				162		162			162
US Premium Financing Holding Company | Initial Fair Value Adjustments
Assets
Total assets				21,314		21,314			21,314
Liabilities
Deferred tax liability				5,492		5,492			5,492
Total liabilities				5,492		5,492			5,492
Net identifiable assets acquired over (under) liabilities assumed				15,822		15,822			15,822
Goodwill				67,159		67,159			67,159
Net assets acquired over liabilities assumed				82,981		82,981			82,981
US Premium Financing Holding Company | Initial Fair Value Adjustments | Insurance Agent Relationships
Assets
Other intangible assets, net				20,000		20,000			20,000
US Premium Financing Holding Company | Initial Fair Value Adjustments | Trade Names
Assets
Other intangible assets, net				1,136		1,136			1,136
US Premium Financing Holding Company | Initial Fair Value Adjustments | Noncompete Agreements
Assets
Other intangible assets, net				178		178			178
US Premium Financing Holding Company | Subsequent Adjustments
Assets
Total assets				2,293		2,293			2,293
Liabilities
Deferred tax liability				(368)		(368)			(368)
Total liabilities				(368)		(368)			(368)
Net identifiable assets acquired over (under) liabilities assumed				2,661		2,661			2,661
Goodwill				(2,661)		(2,661)			(2,661)
Net assets acquired over liabilities assumed				0		0			0
US Premium Financing Holding Company | Subsequent Adjustments | Insurance Agent Relationships
Assets
Other intangible assets, net				2,351		2,351			2,351
US Premium Financing Holding Company | Subsequent Adjustments | Trade Names
Assets
Other intangible assets, net				(42)		(42)			(42)
US Premium Financing Holding Company | Subsequent Adjustments | Noncompete Agreements
Assets
Other intangible assets, net				(16)		(16)			(16)
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
Liabilities
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
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
Liabilities
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
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
Liabilities
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
Previously Reported | US Premium Financing Holding Company
Assets
Total assets				0		0			0
Liabilities
Deferred tax liability				0		0			0
Total liabilities				0		0			0
Net identifiable assets acquired over (under) liabilities assumed				0		0			0
Goodwill				0		0			0
Net assets acquired over liabilities assumed				0		0			0
Previously Reported | US Premium Financing Holding Company | Insurance Agent Relationships
Assets
Other intangible assets, net				0		0			0
Previously Reported | US Premium Financing Holding Company | Trade Names
Assets
Other intangible assets, net				0		0			0
Previously Reported | US Premium Financing Holding Company | Noncompete Agreements
Assets
Other intangible assets, net				$ 0		$ 0			$ 0
Weighted Average | US Premium Financing Holding Company
Liabilities
Price per share of the Company's common stock (in dollars per share)				$ 52.047		$ 52.047			$ 52.047