Concentrations of Risk (Narrative) (Details) - manufacturer	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Number of third-party manufacturers	114	112	114	112
Sales | Product Concentration Risk | Top 5 Customers
Concentration Risk [Line Items]
Concentration risk, percentage	39.90%	40.40%	41.20%	41.40%
Sales | Customer Concentration Risk | Walmart
Concentration Risk [Line Items]
Concentration risk, percentage	21.40%	20.40%	24.00%	20.70%
Sales | Customer Concentration Risk | Walgreens
Concentration Risk [Line Items]
Concentration risk, percentage	9.20%	10.00%	9.00%	10.30%
Sales | Supplier Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage			74.20%	78.50%
Number of third-party manufacturers with long-term contracts			46	48
Accounts Receivable | Customer Concentration Risk | Walmart
Concentration Risk [Line Items]
Concentration risk, percentage			24.10%
Accounts Receivable | Customer Concentration Risk | Walgreens
Concentration Risk [Line Items]
Concentration risk, percentage			9.30%