Quarterly Financial Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Interim Period, Costs Not Allocable [Line Items]
Net Sales	$ 820.7	$ 856.9	$ 869.2	$ 813.5	$ 758.1	$ 809.6	$ 838.6	$ 818.2	$ 3,360.3	$ 3,224.5	$ 3,509.7
Gross Profit	218.5	227.0	223.0	215.6	193.2	231.7	222.9	217.4	884.1	865.2	933.2
Income from Operations	78.3	94.0	83.0	74.8	70.1	89.8	91.4	69.3	330.1	320.6	252.8
Net Income	52.6	63.6	54.3	47.6	47.1	61.1	58.4	42.7	218.1	209.3	148.5
Net Income Attributable to Regal Beloit Corporation	$ 51.5	$ 62.2	$ 53.0	$ 46.3	$ 45.6	$ 59.6	$ 56.6	$ 41.6	$ 213.0	$ 203.4	$ 143.3
Basic (in dollars per shares)	$ 1.16	$ 1.40	$ 1.19	$ 1.03	$ 1.02	$ 1.33	$ 1.27	$ 0.93	$ 4.78	$ 4.55	$ 3.21
Assuming Dilution (in dollars per share)	$ 1.15	$ 1.39	$ 1.18	$ 1.02	$ 1.01	$ 1.32	$ 1.26	$ 0.93	$ 4.74	$ 4.52	$ 3.18
Basic (in shares)	44.3	44.4	44.7	44.8	44.8	44.8	44.7	44.7	44.6	44.7	44.7
Assuming Dilution (in shares)	44.7	44.8	45.1	45.1	45.1	45.0	45.0	45.0	44.9	45.0	45.1
Goodwill Impairment									$ 0.0	$ 0.0	$ 79.9
Commercial and Industrial Systems
Interim Period, Costs Not Allocable [Line Items]
Net Sales	$ 407.7	$ 408.0	$ 407.4	$ 381.2	$ 369.2	$ 389.4	$ 394.7	$ 377.6	1,604.3	1,530.9	1,694.9
Income from Operations	24.0	29.6	20.6	25.8	20.5	36.2	25.1	21.7
Climate Solutions
Interim Period, Costs Not Allocable [Line Items]
Net Sales	216.4	256.0	270.5	247.7	215.2	250.5	254.5	239.8	990.6	960.0	1,041.2
Income from Operations	30.4	38.8	40.2	31.2	27.0	42.2	36.1	24.6
Power Transmission Solutions
Interim Period, Costs Not Allocable [Line Items]
Net Sales	196.6	192.9	191.3	184.6	173.7	169.7	189.4	200.8	$ 765.4	$ 733.6	$ 773.6
Income from Operations	$ 23.9	$ 25.6	$ 22.2	$ 17.8	$ 22.6	$ 11.4	$ 30.2	$ 23.0