Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Straight-line rent adjustments recorded as a receivable	$ 57.5	$ 51.9

Amount of the adjustment to rental revenues to measure escalating leasing revenues on a straight line basis.

No definition available.

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