Supplemental Guarantor Consolidating Financial Statements - Supplemental Guarantor Consolidating Balance Sheets (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current Assets:
Cash and cash equivalents	$ 1,271.6	$ 1,196.6	$ 1,094.1	$ 1,137.7
Accounts receivable	2,746.5	2,590.0
Inventories	1,020.6	947.6
Intercompany accounts	0.0	0.0
Other	610.6	552.4
Total current assets	5,649.3	5,286.6
Long-Term Assets:
Property, plant and equipment, net	2,019.3	1,826.5
Goodwill	1,121.3	1,053.8	726.2
Investments in subsidiaries	0.0	0.0
Intercompany loans receivable	0.0	0.0
Other	1,110.7	1,238.9
Total long-term assets	4,251.3	4,119.2
Total assets	9,900.6	9,405.8
Current Liabilities:
Short-term borrowings	8.6	0.0
Accounts payable and drafts	2,640.5	2,504.4
Accrued liabilities	1,497.6	1,312.1
Intercompany accounts	0.0	0.0
Current portion of long-term debt	35.6	23.1
Total current liabilities	4,182.3	3,839.6
Long-Term Liabilities:
Long-term debt	1,898.0	1,931.7
Intercompany loans payable	0.0	0.0
Other	627.4	616.8
Total long-term liabilities	2,525.4	2,548.5
Equity:
Lear Corporation stockholders’ equity	3,057.2	2,927.4
Noncontrolling interests	135.7	90.3
Equity	3,192.9	3,017.7	3,029.3	3,149.5
Total liabilities and equity	9,900.6	9,405.8
Eliminations
Current Assets:
Cash and cash equivalents	0.0	0.0	0.0	0.0
Accounts receivable	0.0	0.0
Inventories	0.0	0.0
Intercompany accounts	(181.3)	(125.4)
Other	0.0	0.0
Total current assets	(181.3)	(125.4)
Long-Term Assets:
Property, plant and equipment, net	0.0	0.0
Goodwill	0.0	0.0
Investments in subsidiaries	(4,905.7)	(4,987.7)
Intercompany loans receivable	(1,606.9)	(1,191.9)
Other	(17.8)	(25.1)
Total long-term assets	(6,530.4)	(6,204.7)
Total assets	(6,711.7)	(6,330.1)
Current Liabilities:
Short-term borrowings	0.0
Accounts payable and drafts	0.0	0.0
Accrued liabilities	0.0	0.0
Intercompany accounts	(181.3)	(125.4)
Current portion of long-term debt	0.0	0.0
Total current liabilities	(181.3)	(125.4)
Long-Term Liabilities:
Long-term debt	0.0	0.0
Intercompany loans payable	(1,606.9)	(1,191.9)
Other	(17.8)	(25.1)
Total long-term liabilities	(1,624.7)	(1,217.0)
Equity:
Lear Corporation stockholders’ equity	(4,905.7)	(4,987.7)
Noncontrolling interests	0.0	0.0
Equity	(4,905.7)	(4,987.7)
Total liabilities and equity	(6,711.7)	(6,330.1)
Lear
Current Assets:
Cash and cash equivalents	480.4	526.4	377.8	343.5
Accounts receivable	314.0	334.5
Inventories	67.9	73.5
Intercompany accounts	87.0	53.0
Other	119.4	122.3
Total current assets	1,068.7	1,109.7
Long-Term Assets:
Property, plant and equipment, net	309.4	257.5
Goodwill	172.1	172.1
Investments in subsidiaries	4,002.3	3,520.3
Intercompany loans receivable	308.9	277.5
Other	456.6	622.2
Total long-term assets	5,249.3	4,849.6
Total assets	6,318.0	5,959.3
Current Liabilities:
Short-term borrowings	0.0
Accounts payable and drafts	328.8	322.7
Accrued liabilities	228.6	233.3
Intercompany accounts	0.0	0.0
Current portion of long-term debt	34.4	21.9
Total current liabilities	591.8	577.9
Long-Term Liabilities:
Long-term debt	1,893.5	1,925.3
Intercompany loans payable	504.9	221.6
Other	270.6	307.1
Total long-term liabilities	2,669.0	2,454.0
Equity:
Lear Corporation stockholders’ equity	3,057.2	2,927.4
Noncontrolling interests	0.0	0.0
Equity	3,057.2	2,927.4
Total liabilities and equity	6,318.0	5,959.3
Guarantors
Current Assets:
Cash and cash equivalents	0.3	0.4	0.0	0.1
Accounts receivable	238.7	246.4
Inventories	364.7	337.5
Intercompany accounts	94.3	72.4
Other	15.3	17.5
Total current assets	713.3	674.2
Long-Term Assets:
Property, plant and equipment, net	313.4	294.3
Goodwill	519.9	519.1
Investments in subsidiaries	903.4	1,467.4
Intercompany loans receivable	1,206.9	836.7
Other	146.8	148.0
Total long-term assets	3,090.4	3,265.5
Total assets	3,803.7	3,939.7
Current Liabilities:
Short-term borrowings	0.0
Accounts payable and drafts	460.1	436.5
Accrued liabilities	197.5	187.7
Intercompany accounts	0.0	0.0
Current portion of long-term debt	0.0	0.0
Total current liabilities	657.6	624.2
Long-Term Liabilities:
Long-term debt	0.0	0.0
Intercompany loans payable	48.7	23.5
Other	13.2	22.1
Total long-term liabilities	61.9	45.6
Equity:
Lear Corporation stockholders’ equity	3,084.2	3,269.9
Noncontrolling interests	0.0	0.0
Equity	3,084.2	3,269.9
Total liabilities and equity	3,803.7	3,939.7
Non- guarantors
Current Assets:
Cash and cash equivalents	790.9	669.8	$ 716.3	$ 794.1
Accounts receivable	2,193.8	2,009.1
Inventories	588.0	536.6
Intercompany accounts	0.0	0.0
Other	475.9	412.6
Total current assets	4,048.6	3,628.1
Long-Term Assets:
Property, plant and equipment, net	1,396.5	1,274.7
Goodwill	429.3	362.6
Investments in subsidiaries	0.0	0.0
Intercompany loans receivable	91.1	77.7
Other	525.1	493.8
Total long-term assets	2,442.0	2,208.8
Total assets	6,490.6	5,836.9
Current Liabilities:
Short-term borrowings	8.6
Accounts payable and drafts	1,851.6	1,745.2
Accrued liabilities	1,071.5	891.1
Intercompany accounts	181.3	125.4
Current portion of long-term debt	1.2	1.2
Total current liabilities	3,114.2	2,762.9
Long-Term Liabilities:
Long-term debt	4.5	6.4
Intercompany loans payable	1,053.3	946.8
Other	361.4	312.7
Total long-term liabilities	1,419.2	1,265.9
Equity:
Lear Corporation stockholders’ equity	1,821.5	1,717.8
Noncontrolling interests	135.7	90.3
Equity	1,957.2	1,808.1
Total liabilities and equity	$ 6,490.6	$ 5,836.9