Consolidated Statements Of Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net sales	$ 3,943.8	$ 3,749.9	$ 3,917.2
Cost of goods sold	3,075.9	2,850.7	2,994.0
Gross profit	867.9	899.2	923.2
Selling and administrative expenses	403.6	396.8	416.9
Amortization of intangibles	20.7	19.9	20.8
Impairments	4.9	4.1	6.3
Gain on sale of assets and businesses	(24.2)	(37.6)	(0.5)
Other (income) expense, net	(5.0)	(6.0)	(6.8)
Earnings from continuing operations before interest and income taxes	467.9	522.0	486.5
Interest expense	43.5	38.8	41.1
Interest income	7.6	3.9	4.4
Earnings from continuing operations before income taxes	432.0	487.1	449.8
Income taxes	138.4	120.0	121.8
Earnings from continuing operations	293.6	367.1	328.0
Earnings (loss) from discontinued operations, net of tax	(0.9)	19.1	1.2
Net earnings	292.7	386.2	329.2
(Earnings) attributable to noncontrolling interest, net of tax	(0.1)	(0.4)	(4.1)
Net earnings attributable to Leggett & Platt, Inc. common shareholders	$ 292.6	$ 385.8	$ 325.1
Earnings per share from continuing operations attributable to Leggett & Platt, Inc. common shareholders
Basic (in dollars per share)	$ 2.16	$ 2.66	$ 2.30
Diluted (in dollars per share)	2.14	2.62	2.27
Earnings (loss) per share from discontinued operations attributable to Leggett & Platt, Inc. common shareholders
Basic (in dollars per share)	(0.01)	0.14	0.01
Diluted (in dollars per share)	(0.01)	0.14	0.01
Net earnings per share attributable to Leggett & Platt, Inc. common shareholders
Basic (in dollars per share)	2.15	2.80	2.31
Diluted (in dollars per share)	$ 2.13	$ 2.76	$ 2.28