Reconciliation of Numerators and Denominators of Basic and Diluted Net Income Attributable to Canon Inc. Stockholders Per Share Computations (Detail) (JPY ¥) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Earnings Per Share Disclosure [Line Items]
Net income attributable to Canon Inc.	¥ 248,630	¥ 246,603	¥ 131,647
Average common shares outstanding	1,215,832,419	1,234,817,434	1,234,481,836
Stock options	60,552	50,603
Diluted common shares outstanding	1,215,892,971	1,234,868,037	1,234,481,836
Net income attributable to Canon Inc. stockholders per share:
Basic	¥ 204.49	¥ 199.71	¥ 106.64
Diluted	¥ 204.48	¥ 199.70	¥ 106.64

Reconciliation of Numerators and Denominators of Basic and Diluted Net Income Attributable to Canon Inc. Stockholders Per Share Computations (Detail) (JPY ¥)
In Millions, except Share data, unless otherwise specified

12 Months Ended

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2009

Earnings Per Share Disclosure [Line Items]

Net income attributable to Canon Inc.

¥ 248,630

¥ 246,603

¥ 131,647

Average common shares outstanding

1,215,832,419

1,234,817,434

1,234,481,836

Stock options

60,552

50,603

Diluted common shares outstanding

1,215,892,971

1,234,868,037

1,234,481,836

Net income attributable to Canon Inc. stockholders per share:

Basic

¥ 204.49

¥ 199.71

¥ 106.64

Diluted

¥ 204.48

¥ 199.70

¥ 106.64

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References+ Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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