Employee Benefit Plan (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended	6 Months Ended
Mar. 31, 2011	Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2010 NGL Supply, Inc.
Employee Benefit Plan
Contributions to the 401(k) defined contribution plan	$ 0.2	$ 1.9	$ 0.5	$ 0.1

Amount of discretionary contributions made by an employer to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration