Interest and Other Income, net - Schedule Of Interest And Other Income, net (Parenthetical) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Preferred equity ownership percentage	24.40%
PGRESS Equity Holdings L.P. [Member]
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Preferred equity investment income, attributable to parent	$ 111	$ 219
Preferred equity ownership percentage	24.40%