ACQUISITIONS Acquisitions (Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Combinations [Abstract]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 316,600	$ 341,900	$ 344,000	$ 295,600	$ 288,200	$ 311,100	$ 305,300	$ 220,300	$ 1,298,129	$ 1,124,909	$ 949,856
Business Acquisition, Pro Forma Revenue									1,298,100	1,184,800	1,144,600
Net Income Attributable to Franklin Electric Co., Inc.	$ 24,200	$ 30,000	$ 30,500	$ 21,200	$ 8,100	$ 24,500	$ 29,900	$ 15,700	105,877	78,180	78,745
Business Acquisition, Pro Forma Net Income (Loss)									$ 105,900	$ 79,400	$ 85,000
Earnings Per Share, Basic	$ 0.51	$ 0.64	$ 0.65	$ 0.45	$ 0.17	$ 0.52	$ 0.64	$ 0.33	$ 2.25	$ 1.67	$ 1.67
Business Acquisition, Pro Forma Earnings Per Share, Basic									2.25	1.70	1.80
Earnings Per Share, Diluted	$ 0.51	$ 0.63	$ 0.64	$ 0.45	$ 0.17	$ 0.52	$ 0.64	$ 0.33	2.23	1.65	1.65
Business Acquisition, Pro Forma Earnings Per Share, Diluted									$ 2.23	$ 1.68	$ 1.78