Components of Stock Based Compensation (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation					$ 20.2		$ 18.3
To be settled with stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	5.8		5.3		14.1		13.4
Employee contributions for above stock plans	2.9		2.5		6.1		4.9
Total stock-based compensation	8.7		7.8		20.2		18.3
Recognized tax benefits on stock-based compensation expense	2.3		2.0		5.4		5.1
To be settled with stock | Amortization of the grant date fair value
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0.5	[1]	0.9	[1]	1.0	[1]	3.2	[1]
To be settled with stock | Cash payments in lieu of options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0	[1]	0	[1]	0	[1]	0	[1]
To be settled with stock | Stock-based retirement plans contributions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	1.6		1.4		3.9		3.3
To be settled with stock | Deferred Stock Compensation Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0.3		0.1		1.0		0.6
To be settled with stock | Stock-based retirement plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0.2		0.2		0.7		0.7
To be settled with stock | Discount Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0.2		0.3		0.5		0.5
To be settled with stock | Performance Stock Unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	1.6	[2]	1.6	[2]	3.2	[2]	3.3	[2]
To be settled with stock | Profitable Growth Incentive awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0.3	[1]	0	[1]	0.5	[1]	0	[1]
To be settled with stock | Restricted Stock Unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0.9		0.6		2.6		1.4
To be settled with stock | Other, primarily non-employee directors restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0.2		0.2		0.7		0.4
To be settled in cash
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	(0.4)		0.3		5.4		0.9
To be settled in cash | Amortization of the grant date fair value
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0	[1]	0	[1]	0	[1]	0	[1]
To be settled in cash | Cash payments in lieu of options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0	[1]	0	[1]	0.8	[1]	0.3	[1]
To be settled in cash | Stock-based retirement plans contributions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0.2		0.2		0.7		0.6
To be settled in cash | Deferred Stock Compensation Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0		0		0		0
To be settled in cash | Stock-based retirement plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0		0		0		0
To be settled in cash | Discount Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0		0		0		0
To be settled in cash | Performance Stock Unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	(0.9)	[2]	0.1	[2]	3.4	[2]	0	[2]
To be settled in cash | Profitable Growth Incentive awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0.3	[1]	0	[1]	0.5	[1]	0	[1]
To be settled in cash | Restricted Stock Unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	0		0		0		0
To be settled in cash | Other, primarily non-employee directors restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-related compensation expense	$ 0		$ 0		$ 0		$ 0

[1] Stock Option Grants and Profitable Growth Incentive AwardsOur most significant stock options have historically been granted annually on a discretionary basis to a broad group of employees.Previous to 2013, we offered two different option choice programs. One group of employees was offered the choice to receive stock options or to receive a cash alternative equal to approximately one-half of the Black-Scholes value of the option grant foregone. Another group of employees, generally higher level employees, was offered a choice between stock options or restricted stock units (RSUs), on a ratio of four options foregone for each RSU offered. The RSUs vest in one-third increments at 12 months, 24 months and 36 months after the date of grant.Starting in 2013, options are only offered in conjunction with the Deferred Compensation Program. In addition, certain key management employees participate in a new Profitable Growth Incentive (PGI) program. Options for other employees have been replaced with either cash awards or RSUs as offered in 2011 and 2012. The PGI awards are issued as growth performance stock units (GPSUs). The GPSUs vest (0% to 250%) at the end of a two-year performance period. Vesting is based on the Company's or applicable profit center's Revenue Growth adjusted by a GDP factor when applicable and EBITDA Margin of the Company or applicable profit center at the end of a two-year performance period. The 2013 base PGI award was 130,920 shares. We intend to pay half in shares of our common stock and half in cash, although we reserve the right to pay up to 100% in cash. Both components are adjusted to fair value at each reporting period.

[2] Performance Stock Unit AwardsWe also grant Performance Stock Unit (PSU) awards in the first quarter of each year to selected officers and other key managers. These awards contain the following conditions:•A service requirement—Awards generally “cliff” vest three years following the grant date; and•A market condition—Awards are based on our Total Shareholder Return [TSR = (Change in Stock Price + Dividends) / Beginning Stock Price] as compared to the TSR of a group of peer companies. The peer group consists of all the companies in the Industrial, Materials and Consumer Discretionary sectors of the S&P 500 and S&P Midcap 400 (approximately 320 companies). Participants will earn from 0% to 175% of the base award depending upon how our Total Shareholder Return ranks within the peer group at the end of the 3-year performance period.Below is a summary of the number of shares and related grant date fair value of PSU’s for the periods presented. Grant date fair values are calculated using a Monte Carlo simulation of stock and volatility data for Leggett and each of the comparator companies and are based upon assumptions listed below. Grant date fair values are amortized using the straight-line method over the three-year vesting period. Six Months EndedJune 30, 2013 2012Total shares base award234,117 282,040Grant date per share fair value$27.60 $23.79Risk-free interest rate.4% .4%Expected life in years3.0 3.0Expected volatility (over expected life)29.1% 35.0%Expected dividend yield (over expected life)4.2% 4.8%The three-year performance cycle of the 2010 award was completed on December 31, 2012. Our TSR performance, relative to the peer group, ranked at 46th percentile (with 1% being best); accordingly, participants earned 91.0% of the base award and .3 million shares were distributed in January 2013. The above information represents the 65% portion of the award that we intend to pay in shares of our common stock, although we reserve the right to pay up to 100% in cash. There is also an additional amount that represents 35% of the award that we will settle in cash. It is recorded as a liability and is adjusted to fair value at each reporting period.