Condensed Financial Information of Fidelity Southern Corporation (Parent Company Only) - Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest income
Total interest income	$ 157,978	$ 149,283	$ 116,642
Net interest income	135,248	128,835	100,838
Other	2,991	2,632	5,892
Total noninterest income	134,952	141,325	127,888
Noninterest expense	210,870	201,020	162,946
Income before income tax expense	55,055	60,909	61,429
Income tax benefit	15,259	22,143	22,294
Net income	39,796	38,766	39,135
Parent Company
Interest income
Deposits in bank subsidiary	0	7	9
Subordinated loan to bank subsidiary	437	385	343
Total interest income	437	392	352
Interest expense on subordinated debt	1,550	1,311	1,122
Net interest income	(1,113)	(919)	(770)
Dividends from subsidiaries	10,500	6,800	3,500
Other	107	104	98
Total noninterest income	10,607	6,904	3,598
Noninterest expense	1,269	1,983	2,825
Income before income tax expense	8,225	4,002	3
Income tax benefit	(299)	(1,083)	(1,492)
Income before equity in undistributed net income of subsidiaries	8,524	5,085	1,495
Equity in undistributed net income of subsidiaries	31,272	33,681	37,640
Net income	$ 39,796	$ 38,766	$ 39,135