Summary of Significant Accounting Policies Tax (Parenthetical) (Details) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Disclosure Summary Of Significant Accounting Policies Tax Parenthetical Details [Abstract]
Dividend payable common share/unit, per share	$ 0.54	$ 0.50375

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Name:	us-gaap_DividendsPayableAmountPerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant