XML 71 R50.htm IDEA: XBRL DOCUMENT v3.8.0.1
Summary of Significant Accounting Policies - Summary of Information Used to Compute Basic and Diluted Net Income Per Share (Detail) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
Jul. 01, 2017
Apr. 01, 2017
Dec. 31, 2016
Oct. 01, 2016
Jul. 02, 2016
Apr. 02, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Accounting Policies [Abstract]                      
Net income attributable to Lear $ 400.5 $ 295.2 $ 311.9 $ 305.8 $ 229.9 $ 214.4 $ 282.4 $ 248.4 $ 1,313.4 $ 975.1 $ 745.5
Less: Redeemable noncontrolling interest adjustment                 (25.5) 0.0 0.0
Net income available to Lear common stockholders                 $ 1,287.9 $ 975.1 $ 745.5
Average common shares outstanding (in shares)                 68,542,363 72,345,436 76,754,270
Dilutive effect of common stock equivalents (in shares)                 735,618 779,513 1,012,747
Average diluted shares outstanding (in shares)                 69,277,981 73,124,949 77,767,017
Basic net income per share available to Lear common stockholders (in dollars per share) $ 5.89 $ 4.00 $ 4.53 $ 4.39 $ 3.28 $ 3.01 $ 3.85 $ 3.33 $ 18.79 $ 13.48 $ 9.71
Diluted net income per share available to Lear common stockholders (in dollars per share) $ 5.80 $ 3.96 $ 4.49 $ 4.35 $ 3.24 $ 2.98 $ 3.82 $ 3.29 $ 18.59 $ 13.33 $ 9.59