Debt (Schedule Of Notes Payable And Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Debt Instrument [Line Items]
Interest Expense, Debt	$ 2	$ 2	$ 5	$ 4
Short-term Debt, Weighted Average Interest Rate	0.10%		0.10%		0.20%
Debt, Current	129		129		383
Long-term Debt, Weighted Average Interest Rate	3.40%		3.40%		3.40%
Commercial Paper [Member]
Debt Instrument [Line Items]
Short-term Debt	129		129		381
Short-term Debt, Weighted Average Interest Rate	0.10%		0.10%		0.20%
$200.0 European Revolving Credit Facility, Due March 13, 2014 [Member]
Debt Instrument [Line Items]
Short-term Debt	0		0		0
Short-term Debt, Weighted Average Interest Rate	0.00%		0.00%		0.00%
Sigma-Aldrich Korea Limited Credit Facility, Due June 30, 2014 [Member]
Debt Instrument [Line Items]
Short-term Debt	0		0		0
Short-term Debt, Weighted Average Interest Rate	0.00%		0.00%		0.00%
Sigma-Aldrich Japan Credit Facility [Member]
Debt Instrument [Line Items]
Short-term Debt	0		0		0
Short-term Debt, Weighted Average Interest Rate	0.00%		0.00%		0.00%
Other Short-Term Credit Facilities [Member]
Debt Instrument [Line Items]
Short-term Debt	0		0		2
Short-term Debt, Weighted Average Interest Rate	0.00%		0.00%		1.50%
Senior Notes, Due November 1, 2020 [Member]
Debt Instrument [Line Items]
Outstanding	300		300
Long-term Debt, Weighted Average Interest Rate, Noncurrent Maturities	3.40%		3.40%		3.40%
Total Notes Payable [Member]
Debt Instrument [Line Items]
Short-term Debt	129		129		383
Long-Term Debt [Member] | Senior Notes, Due November 1, 2020 [Member]
Debt Instrument [Line Items]
Outstanding	300		300		300
Total Long-Term Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities	$ 300		$ 300		$ 300