Consolidated Statements of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net sales	$ 17,045.5	$ 19,810.3	$ 21,148.5
Cost of sales	15,936.6	18,072.8	18,830.2
Selling, general and administrative expenses	588.9	605.0	612.8
Amortization of intangible assets	65.9	62.3	51.4
Interest expense	99.6	92.0	84.1
Other expense, net	55.2	24.6	31.6
Consolidated income before provision for income taxes and equity in net income of affiliates	299.3	953.6	1,538.4
Provision for income taxes	93.9	146.1	311.9
Equity in net income of affiliates	(28.5)	(23.2)	(20.2)
Consolidated net income	233.9	830.7	1,246.7
Less: Net income attributable to noncontrolling interests	75.4	77.1	96.9
Net income attributable to Lear	$ 158.5	$ 753.6	$ 1,149.8
Basic net income per share available to Lear common stockholders (in dollars per share)	$ 2.63	$ 12.80	$ 17.35
Diluted net income per share available to Lear common stockholders (in dollars per share)	$ 2.62	$ 12.75	$ 17.22
Average common shares outstanding (in shares)	60,254,380	61,697,192	65,672,164
Average diluted shares outstanding (in shares)	60,426,962	61,923,528	66,161,816