Quarterly Data (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Jan. 02, 2021	Oct. 03, 2020	Jul. 04, 2020	Apr. 04, 2020	Jan. 04, 2020	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Jan. 02, 2021	Jan. 04, 2020	Dec. 29, 2018
Summary of quarterly data
Total revenues	$ 3,667	$ 2,735	$ 2,472	$ 2,777	$ 4,035	$ 3,259	$ 3,227	$ 3,109	$ 11,651	$ 13,630	$ 13,972
Special charges	(23)	(7)	(78)	(39)	(72)	0	0	0	(147)	(72)	(73)
Inventory charge	0	0	(55)	0	0	0	0	0
Income tax benefit (expense)	21	(1)	26	(19)	(11)	(21)	(62)	(33)	$ 27	$ (127)	$ (162)
Net income (loss)	$ 236	$ 115	$ (92)	$ 50	$ 199	$ 220	$ 217	$ 179
Earnings Per Share [Abstract]
Basic earnings per share - continuing operations (in dollars per share)	$ 1.03	$ 0.50	$ (0.40)	$ 0.22	$ 0.87	$ 0.96	$ 0.94	$ 0.76	$ 1.35	$ 3.52	$ 4.88
Diluted earnings per share - continuing operations (in dollars per share)	$ 1.03	$ 0.50	$ (0.40)	$ 0.22	$ 0.87	$ 0.95	$ 0.93	$ 0.76	$ 1.35	$ 3.50	$ 4.83
Basic average shares outstanding (in shares)	228,666	228,918	228,247	228,311	228,653	229,755	232,013	234,839	228,536	231,315	250,196
Diluted weighted-average shares outstanding (in shares)	229,365	229,279	228,247	228,927	229,790	231,097	233,545	236,437	228,979	232,709	253,237
Segment profit margins
Segment profit (loss) margins	8.80%	6.90%	3.30%	5.60%	8.40%	9.10%	10.50%	9.50%
Operating Segment
Summary of quarterly data
Total revenues									$ 11,651	$ 13,630	$ 13,972
Segment Profit	$ 324	$ 189	$ 82	$ 156	$ 340	$ 297	$ 339	$ 294
Corporate
Summary of quarterly data
Corporate expenses and other, net	(50)	(28)	(30)	(14)	(22)	(17)	(24)	(47)
Special charges									(4)	(5)
Reconciling Items
Summary of quarterly data
Corporate expenses and other, net									(122)	(110)	(119)
Special charges					(72)				(147)		(73)
Inventory charge									(55)	0	0
Manufacturing group | Reconciling Items
Summary of quarterly data
Interest expense, net for Manufacturing group	(36)	(38)	(37)	(34)	(36)	(39)	(36)	(35)	(145)	(146)	(135)
Textron Aviation
Summary of quarterly data
Total revenues									3,974	5,187	4,971
Textron Aviation | Operating Segment
Summary of quarterly data
Special charges									(65)	(29)
Textron Aviation | Manufacturing group
Summary of quarterly data
Total revenues	$ 1,560	$ 795	$ 747	$ 872	$ 1,729	$ 1,201	$ 1,123	$ 1,134
Segment profit margins
Segment profit (loss) margins	6.90%	(3.60%)	(8.80%)	0.30%	7.80%	8.70%	9.40%	9.30%
Textron Aviation | Manufacturing group | Operating Segment
Summary of quarterly data
Total revenues									3,974	5,187	4,971
Segment Profit	$ 108	$ (29)	$ (66)	$ 3	$ 134	$ 104	$ 105	$ 106
Bell
Summary of quarterly data
Total revenues									3,309	3,254	3,180
Bell | Manufacturing group
Summary of quarterly data
Total revenues	$ 871	$ 793	$ 822	$ 823	$ 961	$ 783	$ 771	$ 739
Segment profit margins
Segment profit (loss) margins	12.60%	15.00%	14.40%	14.00%	12.30%	14.00%	13.40%	14.10%
Bell | Manufacturing group | Operating Segment
Summary of quarterly data
Total revenues									3,309	3,254	3,180
Segment Profit	$ 110	$ 119	$ 118	$ 115	$ 118	$ 110	$ 103	$ 104
Textron Systems
Summary of quarterly data
Total revenues									1,313	1,325	1,464
Textron Systems | Operating Segment
Summary of quarterly data
Special charges									(37)
Textron Systems | Manufacturing group
Summary of quarterly data
Total revenues	$ 357	$ 302	$ 326	$ 328	$ 399	$ 311	$ 308	$ 307
Segment profit margins
Segment profit (loss) margins	13.70%	13.20%	11.30%	7.90%	8.30%	10.00%	15.90%	9.10%
Textron Systems | Manufacturing group | Operating Segment
Summary of quarterly data
Total revenues									1,313	1,325	1,464
Segment Profit	$ 49	$ 40	$ 37	$ 26	$ 33	$ 31	$ 49	$ 28
Industrial
Summary of quarterly data
Total revenues									3,000	3,798	4,291
Industrial | Operating Segment
Summary of quarterly data
Special charges									(41)	(38)	(73)
Industrial | Manufacturing group
Summary of quarterly data
Total revenues	$ 866	$ 832	$ 562	$ 740	$ 927	$ 950	$ 1,009	$ 912
Segment profit margins
Segment profit (loss) margins	6.40%	7.00%	(2.00%)	1.20%	4.70%	4.90%	7.50%	5.50%
Industrial | Manufacturing group | Operating Segment
Summary of quarterly data
Total revenues									3,000	3,798	4,291
Segment Profit	$ 55	$ 58	$ (11)	$ 9	$ 44	$ 47	$ 76	$ 50
Finance
Summary of quarterly data
Finance Revenue	$ 13	$ 13	$ 15	$ 14	$ 19	$ 14	$ 16	$ 17
Total revenues									$ 55	$ 66	$ 66
Segment profit margins
Segment profit (loss) margins	15.40%	7.70%	26.70%	21.40%	57.90%	35.70%	37.50%	35.30%
Finance | Operating Segment
Summary of quarterly data
Segment Profit	$ 2	$ 1	$ 4	$ 3	$ 11	$ 5	$ 6	$ 6