BUSINESS COMBINATIONS - Schedule of Assets And Liabilities Acquired (Details) - USD ($) $ / shares in Units, $ in Thousands						1 Months Ended	3 Months Ended		12 Months Ended
	Jun. 29, 2018	May 25, 2018	Jan. 31, 2018	Jan. 03, 2018	Jan. 18, 2017	Jan. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Jan. 31, 2018	Dec. 31, 2018
Liabilities
Goodwill							$ 501,308	$ 208,513		$ 503,434
Company common stock issued							0	50,011
Cash exchanged for shares							0	$ 21,421
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	$ 1,300,000						1,298,040
Less allowance for loan losses							0
Loans, net							1,298,040
Other real estate owned							847
Premises and equipment							26,760
Other intangible assets, net							23,610
Cash value of bank owned life insurance							4,454
Deferred income taxes, net							6,480
Other assets							13,036
Total assets							1,788,792
Liabilities
Noninterest-bearing							381,039
Interest-bearing							1,204,211
Total deposits							1,585,250
Other borrowings							10,907
Subordinated deferrable interest debentures							2,292
Other liabilities							12,851
Total liabilities							1,611,300
Net identifiable assets acquired over (under) liabilities assumed							177,492
Goodwill	$ 219,600						219,643
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
Company common stock issued	349,400
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 debentures	(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							(696)
Less allowance for loan losses							0
Loans, net							(696)
Other real estate owned							0
Premises and equipment							(723)
Other intangible assets, net							7,610
Cash value of bank owned life insurance							0
Deferred income taxes, net							343
Other assets							(17)
Total assets							6,039
Liabilities
Noninterest-bearing							0
Interest-bearing							4,783
Total deposits							4,783
Other borrowings							286
Subordinated deferrable interest debentures							(143)
Other liabilities							0
Total liabilities							4,926
Net identifiable assets acquired over (under) liabilities assumed							1,113
Goodwill							(1,070)
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							10,896
Other intangible assets, net							7,488
Cash value of bank owned life insurance							18,182
Deferred income taxes, net							8,086
Other assets							3,052
Total assets							875,648
Liabilities
Noninterest-bearing							69,761
Interest-bearing							515,406
Total deposits							585,167
Other borrowings							204,475
Other liabilities							8,354
Total liabilities							797,996
Net identifiable assets acquired over (under) liabilities assumed							77,652
Goodwill		$ 91,600					91,635
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
Company common stock issued		147,800
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							0
Other intangible assets, net							1,551
Cash value of bank owned life insurance							0
Deferred income taxes, net							1,595
Other assets							82
Total assets							750
Liabilities
Noninterest-bearing							0
Interest-bearing							1,025
Total deposits							1,025
Other borrowings							0
Other liabilities							0
Total liabilities							1,025
Net identifiable assets acquired over (under) liabilities assumed							(275)
Goodwill							275
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			$ 44,500	$ 5,500	$ 5,800
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 | 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 debentures	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