Non-controlling Interest - Distributions Paid or Payable (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders	$ 7,306	$ 7,818
Tax and other distributions
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders	2,031	2,794
Dividend distributions
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders	$ 5,275	$ 5,024