Permanent and Temporary Equity (Redeemable OP Unitholder and Noncontrolling Interest) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Increase (Decrease) in Temporary Equity [Roll Forward]
December 31, 2017	$ 158,490
New issuances	34,035
Change in valuation	4,674
Distributions and other	(7,817)
Redemptions	(1,241)
December 31, 2018	188,141
Non- controlling Interests
Increase (Decrease) in Temporary Equity [Roll Forward]
December 31, 2017	12,238
New issuances	0
Change in valuation	1,351
Distributions and other	0
Redemptions	0
December 31, 2018	13,589
General Partner
Increase (Decrease) in Temporary Equity [Roll Forward]
December 31, 2017	146,252
New issuances	34,035
Change in valuation	3,323
Distributions and other	(7,817)
Redemptions	(1,241)
December 31, 2018	$ 174,552