ACQUISITIONS Acquisitions (Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Net sales	$ 320,100	$ 348,400	$ 355,400	$ 290,700	$ 316,600	$ 341,900	$ 344,000	$ 295,600	$ 1,314,578	$ 1,298,129	$ 1,124,909
Business Acquisition, Pro Forma Revenue									1,314,600	1,298,100	1,184,800
Net Income Attributable to Franklin Electric Co., Inc.	$ 19,800	$ 33,900	$ 32,700	$ 9,100	$ 24,200	$ 30,000	$ 30,500	$ 21,200	95,483	105,877	78,180
Business Acquisition, Pro Forma Net Income (Loss)									$ 95,500	$ 105,900	$ 79,400
Earnings Per Share, Basic	$ 0.42	$ 0.73	$ 0.70	$ 0.19	$ 0.51	$ 0.64	$ 0.65	$ 0.45	$ 2.04	$ 2.25	$ 1.67
Business Acquisition, Pro Forma Earnings Per Share, Basic									2.04	2.25	1.70
Earnings Per Share, Diluted	$ 0.42	$ 0.72	$ 0.70	$ 0.19	$ 0.51	$ 0.63	$ 0.64	$ 0.45	2.03	2.23	1.65
Business Acquisition, Pro Forma Earnings Per Share, Diluted									$ 2.03	$ 2.23	$ 1.68