Summary of Revenues from Customers Representing at Least 10% of Total Revenues (Detail) (Sales Revenue, Goods, Net [Member])	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Express Scripts [Member]
Revenue, Major Customer [Line Items]
Percentage of total revenues	60.00%	67.00%
Accredo Health Group, Inc. [Member]
Revenue, Major Customer [Line Items]
Percentage of total revenues	17.00%	0.00%

Percentage of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

No definition available.

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