Declared Common Stock Dividends (Detail) (USD $)	3 Months Ended	12 Months Ended
Jun. 30, 2012	Dec. 31, 2012
Dividends Payable [Line Items]
Per Share	$ 0.20	$ 0.60
Dividend Payment 1st
Dividends Payable [Line Items]
Declaration Date		May 11, 2012
Record Date		Jun. 08, 2012
Payable Date		Jun. 22, 2012
Per Share		$ 0.20
Dividend Payment 2nd
Dividends Payable [Line Items]
Declaration Date		Aug. 20, 2012
Record Date		Sep. 14, 2012
Payable Date		Sep. 28, 2012
Per Share		$ 0.20
Dividend Payment 3rd
Dividends Payable [Line Items]
Declaration Date		Nov. 06, 2012
Record Date		Nov. 30, 2012
Payable Date		Dec. 14, 2012
Per Share		$ 0.20

Aggregate dividends declared during the period for each share of common stock outstanding.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770

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- Definition

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

+ References

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- Definition

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

+ References

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 32

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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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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