PARENT COMPANY STATEMENTS (CONDENSED STATEMENTS OF INCOME) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Other income									$ 2,598	$ 2,213	$ 2,974
Interest expense on subordinated debt	$ (8,769)	$ (7,969)	$ (7,002)	$ (6,066)	$ (5,400)	$ (5,360)	$ (5,082)	$ (4,628)	(29,806)	(20,470)	(16,612)
INCOME BEFORE INCOME TAXES AND EQUITY IN UNDISTRIBUTED INCOME OF SUBSIDIARIES									89,634	77,217	69,200
Income tax benefit	(11,779)	(7,573)	(7,394)	(5,558)	(6,582)	(6,498)	(6,091)	(5,962)	(32,304)	(25,133)	(22,833)
NET INCOME	$ 11,627	$ 15,825	$ 15,364	$ 14,514	$ 13,522	$ 13,480	$ 12,803	$ 12,279	57,330	52,084	46,367
COMPREHENSIVE INCOME									59,047	47,555	44,679
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Other income									57	50	98
Interest expense on subordinated debt									(1,349)	(1,190)	(1,063)
Miscellaneous expense									(6,491)	(5,006)	(3,231)
INCOME BEFORE INCOME TAXES AND EQUITY IN UNDISTRIBUTED INCOME OF SUBSIDIARIES									15,069	15,511	7,092
Income tax benefit									2,688	2,483	1,655
INCOME BEFORE EQUITY IN UNDISTRIBUTED INCOME OF SUBSIDIARIES									17,757	17,994	8,747
Equity in undistributed income of subsidiaries									39,573	34,090	37,620
NET INCOME									57,330	52,084	46,367
COMPREHENSIVE INCOME									59,047	47,555	44,679
Parent Company [Member] | Lake City Bank [Member]
Condensed Financial Statements, Captions [Line Items]
Dividends from Lake City Bank, Lakeland Statutory Trust II									21,822	20,622	10,257
Parent Company [Member] | Non-bank Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Dividends from Lake City Bank, Lakeland Statutory Trust II									$ 1,030	$ 1,035	$ 1,031