Partners' Capital, Mezzanine Capital and Distributions (Changes in Redeemable Noncontrolling Interests) (Details) - USD ($) $ in Thousands		3 Months Ended
	Apr. 14, 2020	Mar. 31, 2021	Mar. 31, 2020
Redeemable Noncontrolling Interest, Equity [Roll Forward]
Balance as of December 31, 2020		$ 141,194
Issuance of preferred units, net of issuance costs		19,561
PIK distribution		4,093
Redemption accretion		698
Tax distributions (1)		(1,891)
Balance as of March 31, 2021		163,655
Subsidiary | Alkali Holdings
Redeemable Noncontrolling Interest, Equity [Roll Forward]
PIK distribution		4,100	$ 3,300
Redemption accretion		$ 700	$ 800
Redeemable Noncontrolling Interest [Line Items]
Equity preferred units issued to pay tax distributions (in shares)		1,860
Equity preferred units issued (in shares)	1,750	18,100