The number of units or equivalent units outstanding for all classes.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB TOPIC 4.F)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187171-122770

Name:	us-gaap_UnitsOfPartnershipInterestAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Organization (Detail) - shares	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization
Units of partnership interest (in shares)	10,479,194	10,491,222	11,491,932
Operating Partnership
Organization
Ownership interest (percent)	94.60%