520 Broad Street Building (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 2014
520 Broad Street Building [Abstract]
Carrying value of the land, building and improvements	$ 37.3

Aggregate of the carrying amounts as of the balance sheet date of investments in building and building improvements.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(d))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Name:	us-gaap_InvestmentBuildingAndBuildingImprovements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant