Non-controlling Interest - Distributions Paid or Payable (Details) - USD ($) $ in Thousands		12 Months Ended
	Feb. 20, 2019	Dec. 31, 2018	Dec. 31, 2017
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders		$ 14,559	$ 17,260
Tax and other distributions
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders		4,511	8,217
Dividend distributions
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders		$ 10,048	$ 9,043
Subsequent Event | Quarterly distribution
Dividends Payable [Line Items]
Distributions declared to non-controlling unitholders	$ 2,600