CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended
	Apr. 03, 2021	Apr. 04, 2020
Income Statement [Abstract]
Net sales	$ 5,354.4	$ 4,457.7
Cost of sales	4,861.6	4,123.5
Selling, general and administrative expenses	168.9	143.7
Amortization of intangible assets	16.5	17.1
Interest expense	22.3	24.4
Other expense, net	6.3	40.5
Consolidated income before provision for income taxes and equity in net income of affiliates	278.8	108.5
Provision for income taxes	58.9	26.5
Equity in net income of affiliates	(5.9)	(1.6)
Consolidated net income	225.8	83.6
Less: Net income attributable to noncontrolling interests	22.1	7.2
Net income attributable to Lear	$ 203.7	$ 76.4
Basic net income per share available to Lear common stockholders (in dollars per share)	$ 3.38	$ 1.26
Diluted net income per share available to Lear common stockholders (in dollars per share)	3.36	1.26
Cash dividends declared per share (in dollars per share)	$ 0.25	$ 0.77
Average common shares outstanding (in shares)	60,312,573	60,509,450
Average diluted shares outstanding (in shares)	60,560,859	60,678,590
Consolidated comprehensive income (loss) (Condensed Consolidated Statements of Equity)	$ 139.4	$ (197.8)
Less: Comprehensive income attributable to noncontrolling interests	21.0	2.4
Comprehensive income (loss) attributable to Lear	$ 118.4	$ (200.2)