Common Stock (Details) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended			9 Months Ended	1 Months Ended	3 Months Ended
Sep. 30, 2010	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010 Parent [Member]	Apr. 30, 2010 Public Offering [Member]	Mar. 31, 2010 Market Equity Offering Program [Member]
Common stock, shares issued		110,647,000	110,225,000		26,000,000	900,000
Public offering price for common stock per share					$ 9.75
Underwriters' purchase of shares to cover over allotments					3,900,000
Proceeds from issuance of common stock	$ 288,470			$ 288,470	$ 279,000	$ 9,500
Average price of common stock under market equity offering program per share						$ 10.77
Sales commission						2.00%

The cash inflow from the additional capital contribution to the entity.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3255-108585

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 18

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 19

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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