Non-controlling Interest - Distributions Paid or Payable (Details) - USD ($)			9 Months Ended
	Feb. 21, 2018	Nov. 01, 2017	Sep. 30, 2017	Sep. 30, 2016
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders	$ 2,512,000	$ 2,261,000	$ 14,213,000	$ 14,094,000
Tax and other distributions
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders			7,430,000	8,442,000
Dividend distributions
Dividends Payable [Line Items]
Distributions paid or payable to or on behalf of non-controlling unitholders			$ 6,783,000	$ 5,652,000