Transactions with Affiliates - Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Transactions with Affiliates
Accounts receivable-affiliates	$ 12,867	$ 4,772
Accounts payable-affiliates	28,469	1,254
WPX Energy
Transactions with Affiliates
Sales to related party	28,026	0	$ 0
Purchases from related party	329,525	0	0
Accounts receivable-affiliates	5,185	0
Accounts payable-affiliates	27,844	0
SemGroup
Transactions with Affiliates
Sales to related party	1,114	606	3,866
Purchases from related party	4,395	5,034	12,254
Accounts receivable-affiliates	71	49
Entities affiliated with management
Transactions with Affiliates
Sales to related party	21,385	268	290
Purchases from related party	4,382	3,870	15,209
Accounts receivable-affiliates	334	24
Accounts payable-affiliates	625	1,246
Equity method investees
Transactions with Affiliates
Sales to related party	0	294	692
Purchases from related party	0	66,820	$ 121,336
Accounts receivable-affiliates	0	6
Accounts payable-affiliates	0	8
NGL Energy Holdings LLC
Transactions with Affiliates
Accounts receivable-affiliates	$ 7,277	$ 4,693

The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle).

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Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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