Financing Activity - Mortgage Loan Activity (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	1 Months Ended
Jun. 30, 2013	Feb. 28, 2013 Lycoming Mall [Member]	Mar. 31, 2010 Lycoming Mall [Member]	Oct. 31, 2009 Lycoming Mall [Member]
Mortgage Loan Activity [Line Items]
Mortagage amount increased	$ 7.9
Initial amount of mortgage loan		28.0
Additional amount drawn		2.1	2.5	5.0
Unamortized balance of mortgage loan		33.4
Total mortgage amount		$ 35.5

The total periodic movement (increases and decreases) in the carrying amount of mortgage loans on real estate.

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 IV)

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 29

-Article 12

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule IV

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-29.6)

-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

Name:	us-gaap_MortgageLoansOnRealEstatePeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration