Consolidated Balance Sheet (Unaudited) (Parenthetical) (USD $) In Millions, except Share data	Sep. 30, 2011	Dec. 31, 2010
Current Assets
Allowance for doubtful accounts	$ 129	$ 104
Inventories classified in Other assets	1,382	1,194
Accumulated depreciation	$ 15,674	$ 13,481
Merck & Co., Inc. Stockholders' Equity
Common stock, par value	$ 0.50	$ 0.50
Common stock, shares authorized	6,500,000,000	6,500,000,000
Common stock, shares issued	3,576,948,356	3,576,948,356
Treasury stock, shares	525,000,622	494,841,533