Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
May 31, 2010	Mar. 31, 2013 Joint Venture Mortgage and Indebtedness	Dec. 31, 2012 Joint Venture Mortgage and Indebtedness
Commitments and Contingencies
Insurance proceeds funded by insurers	$ 50
Minimum insurance coverage	50
Additional insurance proceeds	150
Guarantees of Joint Venture Indebtedness:
Loan guarantee		$ 84.3	$ 84.9

The cash inflow from the amounts received by the insured under the terms of an insurance contract settlement. This element pertains only to insurance proceeds related to operating activities. It excludes insurance settlements classified as investing cash flows, for example, insurance settlements related to fixed assets.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 16

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3337-108585

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 22

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

Name:	us-gaap_ProceedsFromInsuranceSettlementOperatingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration