Forward Equity Agreement Narative (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
Sep. 14, 2010	Sep. 10, 2012
Forward Equity Agreement [Abstract]
Number of common shares covered by forward agreements	24,265,000
Cash received through forward contract		$ 339.1

The maximum number of shares that could be issued to net share settle a contract, if applicable. If a contract does not have a fixed or determinable maximum number of shares that may be required to be issued, disclose the fact that a potentially infinite number of shares could be issued to settle the contract.

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

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 00-19

-Paragraph 50

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 40

-Section 50

-Paragraph 5

-Subparagraph (b)(2)

-URI http://asc.fasb.org/extlink&oid=6445032&loc=d3e90205-114008

Name:	us-gaap_ForwardContractIndexedToIssuersEquityShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration