Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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 210.7-03.16)

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 13, 16

-Article 9

Name:	us-gaap_NotesPayable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Subsequent Events - Additional Information (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Greenwood Forest [Member] Apartments	Jun. 30, 2013 Woodbridge At Lake [Member] Apartments	Aug. 02, 2013 Unsecured Debt [Member] Variable Rate Debt	Jun. 30, 2013 Unsecured Debt [Member] Variable Rate Debt	Aug. 02, 2013 Maximum [Member] Unsecured Debt [Member] Variable Rate Debt
Subsequent Event [Line Items]
Notes Payable	$ 1,671,442,000	$ 1,653,646,000			$ 500,000,000	$ 125,000,000	$ 800,000,000
Number of Units in Real Estate Property	44,219		316	188