Summary of Significant Accounting Policies - Formulary Management Revenue (Details)	12 Months Ended
Dec. 31, 2018
Minimum
Operating results by business segment
Term of formulary management contract	1 year

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_EntityWideRevenueMajorCustomerLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration