SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Dec. 31, 2017	Dec. 31, 2016	Jan. 02, 2016
Quarterly Financial Information Disclosure [Abstract]
Net Sales	$ 288,200	$ 311,100	$ 305,300	$ 220,300	$ 239,600	$ 239,800	$ 252,100	$ 218,400	$ 1,124,909	$ 949,856	$ 924,923
Gross Profit	94,600	103,800	102,800	75,800	81,000	85,500	90,700	74,200	376,982	331,406	297,608
Net income	8,000	24,500	30,200	15,900	17,800	23,700	24,200	13,600	78,593	79,315	73,691
Net Income Attributable to Franklin Electric Co., Inc.	$ 8,100	$ 24,500	$ 29,900	$ 15,700	$ 17,500	$ 23,700	$ 24,000	$ 13,500	$ 78,180	$ 78,745	$ 72,945
Basic Earnings Per Share (in dollars per share)	$ 0.17	$ 0.52	$ 0.64	$ 0.33	$ 0.37	$ 0.51	$ 0.51	$ 0.28	$ 1.67	$ 1.67	$ 1.52
Diluted Earnings Per Share (in dollars per share)	$ 0.17	$ 0.52	$ 0.64	$ 0.33	$ 0.37	$ 0.50	$ 0.50	$ 0.28	$ 1.65	$ 1.65	$ 1.50