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Segment Information - Summary of Revenue by Major Customers (Details) - segment	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting [Abstract]
Number of operating segments	1
Customer Concentration Risk | Sales Revenue, Net | AmerisourceBergen Corp.
Revenue, Major Customer [Line Items]
Percentage of total revenues	20.00%	21.00%	20.00%	20.00%
Customer Concentration Risk | Sales Revenue, Net | Cardinal Health, Inc.
Revenue, Major Customer [Line Items]
Percentage of total revenues	20.00%	19.00%	20.00%	18.00%
Customer Concentration Risk | Sales Revenue, Net | McKesson Corp.
Revenue, Major Customer [Line Items]
Percentage of total revenues	22.00%	25.00%	21.00%	23.00%

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- Definition

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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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