EMPLOYEE STOCK BENEFIT PLANS (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended			12 Months Ended
	Mar. 31, 2011	Feb. 28, 2010	Mar. 31, 2009	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009	Mar. 02, 2011	Feb. 24, 2010	Mar. 11, 2009
Stock-based compensation expense
Pre-tax stock-based compensation expense				$ 39.9	$ 19.7	$ 17.7
Net tax benefit related to stock-based compensation expense				(14.1)	(6.8)	(5.6)
MJN Stock Options
Stock option, Shares
Balance at the beginning of the period (in shares)				1,404,000	997,000
Granted (in shares)				558,000	550,000	1,030,000
Exercised (in shares)				(140,000)	(80,000)
Forfeited or expired (in shares)				(33,000)	(63,000)	(33,000)
Balance at the end of the period (in shares)				1,789,000	1,404,000	997,000
Vested (in shares)				480,000
Vested and expected to vest (in shares)				1,695,000
Stock option, Weighted Average Exercise Price of Shares
Balance at the beginning of the period (in dollars per share)				$ 34.36	$ 26.79
Granted (in dollars per share)				$ 59.18	$ 46.71	$ 26.80
Exercised (in dollars per share)				$ 31.65	$ 26.96
Forfeited or expired (in dollars per share)				$ 45.03	$ 31.82	$ 27.24
Balance at the end of the period (in dollars per share)				$ 42.12	$ 34.36	$ 26.79
Vested (in dollars per share)				$ 33.02
Vested and expected to vest (in dollars per share)				$ 42.12
Stock option, Average Remaining Contractual Term (in years)
Balance at the end of the period (in years)				8.1	8.6	9.2
Vested (in years)				7.5
Vested and expected to vest (in years)				8.1
Stock option, Aggregate Intrinsic Value
Outstanding options				47.6	48.2	26.7
Exercised options				5.2	2.1
Vested options				17.1
Vested and expected to vest options				45.1
Weighted-average grant date fair value of stock options granted (in dollars per share)				$ 14.73	$ 10.31	$ 6.13
Cash proceeds received from options exercised				4.5	2.2
Tax benefit realized from stock options exercised				1.8	0.8
Total unrecognized compensation cost				6.9
Total unrecognized compensation cost expected to be recognized over a weighted average period (in years)				1.8
Stock-based compensation expense
Pre-tax stock-based compensation expense				5.9	3.8	2.6
MJN Stock Options | Black-Scholes Model
Assumptions used to calculate fair value of stock options
Expected volatility (as a percent)				26.70%	23.20%	23.80%
Risk-free interest rate (as a percent)				2.60%	2.70%	2.30%
Dividend yield (as a percent)				1.70%	1.80%	2.90%
Expected life (in years)				6.0	6.0	6.3
Look back period (in years)				6.0	6.0	6.3
MJN Stock Options | Monte Carlo Model
Assumptions used to calculate fair value of stock options
Expected volatility (as a percent)						28.70%
Risk-free interest rate (as a percent)						3.00%
Dividend yield (as a percent)						2.90%
Expected life (in years)						6.8
Look back period (in years)						10
Period of U.S. Treasury yield curve (in years)						10
MJN Performance Share Awards
Stock option, Aggregate Intrinsic Value
Total unrecognized compensation cost				10.0
Total unrecognized compensation cost expected to be recognized over a weighted average period (in years)				1.5
Performance Share Awards
Shares Granted and Earned	275,000	237,000	153,000
Weighted-Average Grant- Date Fair Value (in dollars per share)							$ 57.03	$ 44.38	$ 26.58
Shares outstanding at period end							271,000	219,000	141,000
Percentage of plan performance assumed				100.00%
Stock-based compensation expense
Pre-tax stock-based compensation expense				22.8	5.6	1.3
MJN Restricted Stock Units
Stock option, Aggregate Intrinsic Value
Total unrecognized compensation cost				12.4
Total unrecognized compensation cost expected to be recognized over a weighted average period (in years)				2.6
Nonvested restricted stock units, Shares
Nonvested at the beginning of the period (in shares)				588,000	662,000
Granted (in shares)				134,000	150,000	677,000
Vested (in shares)				(170,000)	(172,000)	(4,000)
Forfeited (in shares)				(19,000)	(52,000)	(11,000)
Nonvested at the end of the period (in shares)				533,000	588,000	662,000
Nonvested restricted stock units, Weighted-Average Grant Date Fair Value
Nonvested at the beginning of the period (in dollars per share)				$ 35.15	$ 34.18
Granted (in dollars per share)				$ 59.40	$ 47.53	$ 34.09
Vested (in dollars per share)				$ 44.44	$ 42.16	$ 44.12
Forfeited (in dollars per share)				$ 40.39	$ 35.37	$ 25.02
Nonvested at the end of the period (in dollars per share)				$ 38.09	$ 35.15	$ 34.18
Stock-based compensation expense
Pre-tax stock-based compensation expense				11.2	10.3	1.4
MJN 2009 Stock Award and Incentive Plan
EMPLOYEE STOCK BENEFIT PLANS
Number of shares approved				25,000,000
MJN 2009 Stock Award and Incentive Plan | MJN Stock Options
EMPLOYEE STOCK BENEFIT PLANS
Under one of the company's vesting schedules, percentage of stock options exercisable on each of the first through the fourth anniversaries of the grant date				25.00%
Under the second of two vesting schedules, percentage of stock options exercisable on each of the first through the third anniversaries of the grant date				33.00%
MJN 2009 Stock Award and Incentive Plan | MJN Stock Options | Upper limit
EMPLOYEE STOCK BENEFIT PLANS
Award expiration (in years)				P10Y
MJN 2009 Stock Award and Incentive Plan | MJN Stock Options | Lower limit
EMPLOYEE STOCK BENEFIT PLANS
Percentage of market price at which executive officers and key employees may be granted options to purchase common stock				100.00%
MJN 2009 Stock Award and Incentive Plan | MJN Performance Share Awards
EMPLOYEE STOCK BENEFIT PLANS
Term of awards (in years)				3 years
Percentage payout based on targets met				200.00%
MJN 2009 Stock Award and Incentive Plan | MJN Restricted Stock Units
EMPLOYEE STOCK BENEFIT PLANS
Restriction expiration from date of grant, minimum (in years)				P1Y
Restriction expiration from date of grant, maximum (in years)				P5Y
BMS Employee Stock Benefit Plans
Nonvested restricted stock units, Weighted-Average Grant Date Fair Value
Increase in compensation expense from accelerated and pro-rata vesting						3.3
Number of MJN restricted stock units awarded to compensate for the lost value in the BMS sponsored employee stock plans (in shares)						300,000
Stock-based compensation expense
Pre-tax stock-based compensation expense						$ 12.4