Real Estate Activities Real Estate Activities - Acquisitions (Details) (901 Market Street [Member], USD $) In Millions, unless otherwise specified	1 Months Ended
Apr. 30, 2013
901 Market Street [Member]
Property, Plant and Equipment [Line Items]
Payments to Acquire Buildings	$ 59.6
Capitalization Rate	5.70%

The cash outflow for acquisition of buildings (properties) whether for investment or use.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

Name:	us-gaap_PaymentsToAcquireBuildings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration