Component of Rental Income and Expense (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Leases, Income Statement, Lease Revenue [Abstract]
Recognition of straight-line rents	$ (2.4)	$ (0.8)	$ (0.8)
Recognition of amortization of above and below market leases	$ 3.6	$ 3.3	$ 3.5

Amount of non-cash amortization of intangible asset (liability) for above and below market leases.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Name:	us-gaap_AmortizationOfAboveAndBelowMarketLeases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration