Basis of Presentation and Summary of Significant Accounting Policies - Weighted Average Interests in Operating Partnership (Details) - Operating Partnership	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Noncontrolling Interest [Line Items]
Parent Company’s weighted average interest in Operating Partnership	97.60%	97.70%	97.70%
Limited partners' weighted average interests in Operating Partnership	2.40%	2.30%	2.30%