Dividends - Dividends Declared and Paid or Payable (Detail) (USD $)	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012
Dividend per Share	$ 0.12	$ 0.12
Dividend 1 [Member]
Date Declared	Jan. 29, 2013	Jan. 31, 2012
Record Date	Feb. 08, 2013	Feb. 10, 2012
Payment Date	Feb. 15, 2013	Feb. 15, 2012
Dividend per Share	$ 0.06	$ 0.06
Dividend 2 [Member]
Date Declared	Apr. 23, 2013	Apr. 19, 2012
Record Date	May 03, 2013	Apr. 30, 2012
Payment Date	May 15, 2013	May 15, 2012
Dividend per Share	$ 0.06	$ 0.06

Date the declared dividend will be paid, in CCYY-MM-DD format.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

+ Details

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- Definition

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

+ References

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- Definition

Date the dividend to be paid was declared, in CCYY-MM-DD format.

+ References

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- Definition

Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

+ References

No definition available.

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