Partners' Capital, Equity and Incentive Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended			6 Months Ended
	Mar. 01, 2020	Jun. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2019	Feb. 28, 2019	Mar. 31, 2017
Partners Capital And Distributions [Line Items]
Proceeds From Issuance Of Common Stock					$ 159,026
Class A Common Stock | Underwritten Offering
Partners Capital And Distributions [Line Items]
Shares under underwritten offering						7,762,500
Shares issued			4,000,000
Common Stock, Capital Shares Reserved for Future Issuance						3,762,500
Share Price						$ 41.50
Proceeds From Issuance Of Common Stock				$ 159,000
Class A Common Stock | At Market
Partners Capital And Distributions [Line Items]
Maximum value of stock which may be issued		$ 400,000			$ 400,000		$ 300,000
Shares issued		0
Forecast | Class A Common Stock | Underwritten Offering
Partners Capital And Distributions [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	3,762,500
Proceeds From Issuance Of Common Stock	$ 147,000