CONSOLIDATED CONDENSED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net sales	$ 1,028.8	$ 960.3
Cost of goods sold	811.4	733.6
Gross profit	217.4	226.7
Selling and administrative expenses	104.7	106.1
Amortization of intangibles	5.0	5.1
Impairments	0.2	0.0
Net (gain) loss from sale of assets and businesses	(0.2)	(0.2)
Other (income) expense, net	0.3	(0.2)
Earnings from continuing operations before interest and income taxes	107.4	115.9
Interest expense	14.4	10.6
Interest income	2.4	2.0
Earnings from continuing operations before income taxes	95.4	107.3
Income taxes	17.5	21.2
Earnings from continuing operations	77.9	86.1
Earnings (loss) from discontinued operations, net of tax	0.0	0.0
Net earnings	77.9	86.1
Earnings attributable to noncontrolling interest, net of tax	0.0	0.0
Net earnings attributable to Leggett & Platt, Inc. common shareholders	$ 77.9	$ 86.1
Earnings per share from continuing operations attributable to Leggett & Platt, Inc. common shareholders
Basic (in dollars per share)	$ 0.58	$ 0.63
Diluted (in dollars per share)	0.57	0.62
Earnings (loss) per share from discontinued operations attributable to Leggett & Platt, Inc. common shareholders
Basic (in dollars per share)	0.00	0.00
Diluted (in dollars per share)	0.00	0.00
Net earnings per share attributable to Leggett & Platt, Inc. common shareholders
Basic (in dollars per share)	0.58	0.63
Diluted (in dollars per share)	0.57	0.62
Cash dividends declared per share (in dollars per share)	$ 0.36	$ 0.34
Weighted average shares outstanding
Basic (in shares)	135.3	136.8
Diluted (in shares)	136.3	138.1