| Subsequent Events - Additional Information (Detail) (USD $) | 3 Months Ended | 6 Months Ended | 1 Months Ended | ||
|---|---|---|---|---|---|
| Jun. 30, 2013 | Jun. 30, 2012 | Jun. 30, 2013 | Jun. 30, 2012 | Jul. 25, 2013
 Subsequent Event | |
| Subsequent Event [Line Items] | |||||
| Dividends declared per share | $ 0.10 | $ 0.10 | $ 0.20 | $ 0.20 | $ 0.10 | 
| Dividends declared, date | Jul. 25, 2013 | ||||
| Dividends declared, payable date | Aug. 28, 2013 | ||||
| Dividends declared, record date | Aug. 10, 2013 | ||||
| X | ||||||||||
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- Definition Aggregate dividends declared during the period for each share of common stock outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition Date the declared dividend will be paid, in CCYY-MM-DD format. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition Date the dividend to be paid was declared, in CCYY-MM-DD format. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format. No definition available. 
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- Details 
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