Equity - Schedule of Economic Interests (Details) - The Company	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Economic interest (as a percent)	41.04%	40.53%
Affiliated Owners
Class of Stock [Line Items]
Economic interest (as a percent)	58.96%	59.47%