Intangible assets written off related to the purchase of the remaining interest in a business

No definition available.

Name:	ngl_IntangibleAssetsWrittenOffRelatedtothePurchaseoftheRemainingInterestinaBusiness
Namespace Prefix:	ngl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 928
-SubTopic 340
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6473545&loc=d3e61844-108004

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsNetAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

+ References

+ Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount before accumulated amortization of intangible assets, excluding goodwill.

+ References

No definition available.

+ Details

Name:	us-gaap_IntangibleAssetsGrossExcludingGoodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph ((a)(1),(b))
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274

+ Details

Name:	us-gaap_IntangibleAssetsNetExcludingGoodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TradeNamesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=ngl_CustomerCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=ngl_PipelineCapacityRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=ngl_RightofwayandEasementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=ngl_WaterRightsDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=ngl_ExecutoryContractsAndOtherAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_NoncompeteAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=ngl_DebtIssuanceCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2018	Mar. 31, 2019
Amortizable
Finite-lived intangible assets, gross	$ 2,241,129		$ 1,301,206
Accumulated amortization	(631,449)		(503,117)
Finite-lived intangible assets, net	1,609,680		798,089
INTANGIBLE ASSETS, net of accumulated amortization	1,612,480		800,889
Non-Amortizable
Gross carrying amount of intangible assets	$ 2,243,929		1,304,006
Weighted average remaining amortization period for intangible assets	18 years 9 months 18 days
Intangible assets written off related to the purchase of the remaining interest in a business		$ 1,800
Trade names
Non-Amortizable
Indefinite-lived intangible assets	$ 2,800		2,800
Customer relationships
Amortizable
Finite-lived intangible assets, gross	1,435,573		742,832
Accumulated amortization	(445,250)		(369,983)
Finite-lived intangible assets, net	$ 990,323		372,849
Customer relationships \| Minimum
Amortizable
Amortizable life	3 years
Customer relationships \| Maximum
Amortizable
Amortizable life	30 years
Customer commitments
Amortizable
Finite-lived intangible assets, gross	$ 502,000		310,000
Accumulated amortization	(111,677)		(74,917)
Finite-lived intangible assets, net	$ 390,323		235,083
Customer commitments \| Minimum
Amortizable
Amortizable life	10 years
Customer commitments \| Maximum
Amortizable
Amortizable life	25 years
Pipeline capacity rights
Amortizable
Amortizable life	30 years
Finite-lived intangible assets, gross	$ 7,799		7,799
Accumulated amortization	(1,647)		(1,387)
Finite-lived intangible assets, net	6,152		6,412
Right-of-way and easements
Amortizable
Finite-lived intangible assets, gross	89,476		73,409
Accumulated amortization	(6,506)		(4,509)
Finite-lived intangible assets, net	$ 82,970		68,900
Right-of-way and easements \| Minimum
Amortizable
Amortizable life	1 year
Right-of-way and easements \| Maximum
Amortizable
Amortizable life	45 years
Water rights
Amortizable
Finite-lived intangible assets, gross	$ 100,937		64,868
Accumulated amortization	(8,441)		(3,018)
Finite-lived intangible assets, net	$ 92,496		61,850
Water rights \| Minimum
Amortizable
Amortizable life	13 years
Water rights \| Maximum
Amortizable
Amortizable life	30 years
Executory contracts and other agreements
Amortizable
Finite-lived intangible assets, gross	$ 48,570		47,230
Accumulated amortization	(18,210)		(17,212)
Finite-lived intangible assets, net	$ 30,360		30,018
Executory contracts and other agreements \| Minimum
Amortizable
Amortizable life	5 years
Executory contracts and other agreements \| Maximum
Amortizable
Amortizable life	30 years
Non-compete agreements
Amortizable
Finite-lived intangible assets, gross	$ 12,723		12,723
Accumulated amortization	(4,735)		(2,570)
Finite-lived intangible assets, net	$ 7,988		10,153
Non-compete agreements \| Minimum
Amortizable
Amortizable life	2 years
Non-compete agreements \| Maximum
Amortizable
Amortizable life	24 years
Debt issuance costs
Amortizable
Finite-lived intangible assets, gross	$ 44,051		42,345
Accumulated amortization	(34,983)		(29,521)
Finite-lived intangible assets, net	$ 9,068		$ 12,824
Debt issuance costs \| Minimum
Amortizable
Amortizable life	3 years
Debt issuance costs \| Maximum
Amortizable
Amortizable life	5 years