Non-controlling Interest - Distributions Paid or Payable (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders	$ 11,259	$ 14,213
Payment Pursuant To Tax Receivable Agreements	5,047	7,296
Distributions declared to non-controlling unitholders	7,536	6,783
Tax and other distributions
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders	3,723	7,430
Dividend distributions
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders	$ 7,536	$ 6,783