Commitments and Contingencies - Insurance, Regulatory Issues and Legal (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Insurance and Regulatory
Period for which insurance policies have been renewed	1 year
Minimum | Claims regarding pricing and associated calculations pertaining to network guarantees
Insurance and Regulatory
Potential loss	$ 0
Maximum | Claims regarding pricing and associated calculations pertaining to network guarantees
Insurance and Regulatory
Potential loss	$ 22,000
AFSC
Insurance and Regulatory
Percentage of total revenues attributable to subsidiary	2.00%	3.00%
Specialty pharmaceutical dispensing operations
Insurance and Regulatory
Period for which insurance policies have been renewed	1 year
Per claim self-insured retention	$ 50
Aggregated self-insured retention	250
General liability
Insurance and Regulatory
Per claim un-aggregated self-insured retention	50
Managed care liability
Insurance and Regulatory
Per claim un-aggregated self-insured retention	1,000
Per class action claim un-aggregated self-insured retention	10,000
Professional liability
Insurance and Regulatory
Per claim un-aggregated self-insured retention	$ 50