For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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-Subparagraph (a)
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Concentrations of Risk (Narrative) (Details) - manufacturer	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Concentration Risk [Line Items]
Number of third-party manufacturers	110	110	110	110
Sales \| Customer Concentration Risk \| Walmart
Concentration Risk [Line Items]
Concentration risk, percentage (percent)	23.60%	25.30%	24.10%	25.40%
Sales \| Customer Concentration Risk \| Walgreens
Concentration Risk [Line Items]
Concentration risk, percentage (percent)	10.00%	8.70%	9.30%	8.90%
Sales \| Supplier Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage (percent)			60.00%	79.50%
Number of third-party manufacturers with long-term contracts			34	45
Top 5 brands \| Sales \| Product Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage (percent)	44.70%	40.80%	43.50%	42.00%