Net Income Per Share Attributable to Lear (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Apr. 01, 2023	Apr. 02, 2022
Earnings Per Share [Abstract]
Net income attributable to Lear	$ 143.6	$ 49.4
Average common shares outstanding (in shares)	59,316,555	59,932,030
Dilutive effect of common stock equivalents (in shares)	242,411	278,949
Average diluted shares outstanding (in shares)	59,558,966	60,210,979
Basic net income per share attributable to Lear (in dollars per share)	$ 2.42	$ 0.82
Diluted net income per share attributable to Lear (in dollars per share)	$ 2.41	$ 0.82