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The number of units converted into shares of each class of partners' capital account. Units represent shares of ownership of the general, limited, and preferred partners.

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Total units issued during the year due to the sale of units. All partners include general, limited and preferred partners.

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The cash outflow for cost incurred directly with the issuance of an equity security.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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The cash inflow from the issuance of preferred limited partners units during the period.

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Price of a single share of a number of saleable stocks of a company.

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Carrying amount, attributable to parent, of an entity's issued and outstanding stock which is not included within permanent equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

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Preferred Units - Additional Information (Detail) - USD ($)	1 Months Ended				12 Months Ended
	Feb. 29, 2016	Jul. 31, 2015	May 31, 2015	Sep. 30, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class Of Stock [Line Items]
Net proceeds from issue and sale of preferred units						$ 26,648,000
Distribution paid					$ 0	$ 0
Preferred stock, shares issued					0	0
Minimum
Class Of Stock [Line Items]
Percentage of preferred unit holders					70.00%
Letter Agreement \| The Gates Foundation \| Series A Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares issued				781,693
Preferred stock, shares issued	361,884		218,646	201,163
Shares exchanged for preferred units		419,809
Letter Agreement \| The Gates Foundation \| Contingently Redeemable Class A Preferred Units
Class Of Stock [Line Items]
Preferred units classified as temporary equity							781,693
Preferred units classified as temporary equity, cost							$ 5,000,000
Class A-3 Preferred Units
Class Of Stock [Line Items]
Units issued and sold during the period	2,005,348
Units sold and issued to investors, per share	$ 7.23
Contingently Redeemable Class A-3 Preferred Stock
Class Of Stock [Line Items]
Units issued and sold during the period	361,884
Units sold and issued to investors, per share	$ 7.23
Class A-3 Preferred Units and Contingently Redeemable Class A-3 Preferred Stock
Class Of Stock [Line Items]
Net proceeds from issue and sale of preferred units	$ 17,100,000
Issuance costs	$ 0
Class B Preferred Units
Class Of Stock [Line Items]
Units issued and sold during the period	1,029,850
Units sold and issued to investors, per share	$ 13.53
Net proceeds from issue and sale of preferred units	$ 13,600,000
Issuance costs	$ 300,000					$ 18,000