Business Combinations - Estimated Fair Value of Assets Acquired and Liabilities Assumed (Detail) (USD $) In Thousands, except Share data, unless otherwise specified				0 Months Ended		0 Months Ended		0 Months Ended		0 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 23, 2013 Prosperity Banking Company [Member]	Sep. 30, 2014 Prosperity Banking Company [Member]	Dec. 23, 2013 Prosperity Banking Company [Member] As Recorded by Acquired Bank [Member]	Dec. 23, 2013 Prosperity Banking Company [Member] Fair Value Adjustments [Member]	Jun. 30, 2014 Coastal Bankshares, Inc. [Member]	Jun. 30, 2014 Coastal Bankshares, Inc. [Member]	Jun. 30, 2014 Coastal Bankshares, Inc. [Member] As Recorded by Acquired Bank [Member]	Jun. 30, 2014 Coastal Bankshares, Inc. [Member] As Recorded by Acquired Bank [Member]	Jun. 30, 2014 Coastal Bankshares, Inc. [Member] Initial Fair Value Adjustments [Member]	Jun. 30, 2014 Coastal Bankshares, Inc. [Member] Subsequent Fair Value Adjustments [Member]
Assets
Cash and cash equivalents				$ 4,285		$ 4,285			$ 3,895		$ 3,895
Federal funds sold and interest-bearing balances				21,687		21,687			15,923		15,923
Investment securities				152,274		151,863	411		66,766		67,266	(500)
Other investments				8,727		8,727			975		975
Mortgage loans held for sale									7,288		7,288
Loans				449,696		487,358	(37,662)		279,441		296,141	(16,700)
Less allowance for loan losses						(6,811)	6,811				(3,218)	3,218
Loans, net				449,696		480,547	(30,851)		279,441		292,923	(13,482)
Other real estate owned				5,623		6,883	(1,260)		8,864		14,992	(3,528)	(2,600)
Premises and equipment				36,293		36,293			11,882		11,882
Intangible assets				4,557		174	4,383		4,773		507	4,266
Other assets				27,792		26,600	1,192		25,334		22,710		2,624
Total assets				710,934		737,059	(26,125)		425,141		438,361	(13,244)	24
Deposits:
Noninterest-bearing				149,242		149,242			80,012		80,012
Interest-bearing				324,441		324,441			289,012		289,012
Total deposits				473,683		473,683			369,024		369,024
Federal funds purchased and securities sold under agreements to repurchase	21,500			21,530		21,530			5,428		5,428
Other borrowings				197,313		185,000	12,313		22,005		22,005
Other liabilities				14,513		14,058	455		6,192		6,192
Subordinated deferrable interest debentures				13,197		29,500	(16,303)		9,052		15,465	(6,413)
Total liabilities				720,236		723,771	(3,535)		411,701		418,114	(6,413)
Net identifiable assets acquired over (under) liabilities assumed				(9,302)		13,288	(22,590)		13,440		20,247	(6,831)
Goodwill	58,879	35,049	956	34,093	34,100		34,093		23,830			23,854	24
Net assets acquired over (under) liabilities assumed				24,791		13,288	11,503		37,270		20,247	17,023
Consideration:
Ameris Bancorp common shares issued				1,168,918		1,168,918		1,598,998		1,598,998
Purchase price per share of the Company's common stock						$ 21.07					$ 21.56
Company common stock issued						24,629					34,474
Cash exchanged for shares						162				2,796
Fair value of total consideration transferred						$ 24,791				$ 37,270