Segment Information (Narrative) (Details) (USD $) In Millions	9 Months Ended
Sep. 30, 2011
Lehigh\Central PA Segment [Member]
Segment Reporting Information [Line Items]
Real Estate, Period Increase (Decrease)	$ 117.3
South Region [Member]
Segment Reporting Information [Line Items]
Real Estate, Period Increase (Decrease)	$ 147.0

Total Increase or Decrease in the carrying amount of real estate investments during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 10

-Section S99

-Paragraph 6

-Subparagraph (SX 210.5-04.(c) Schedule III)

-URI http://asc.fasb.org/extlink&oid=6882300&loc=d3e5864-122674

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 970

-SubTopic 360

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-28.4)

-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

Name:	us-gaap_RealEstatePeriodIncreaseDecrease
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration