Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) Client $ / shares	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Schedule Of Significant Accounting Policies [Line Items]
Outsourced shipping expenses	$ 3,600,000	$ 3,000,000	$ 2,900,000
Number of clients accounted for more than 5% revenue | Client	0
Minimum cost of purchases under Property and equipment	$ 1,000
Property and equipment, life	1 year
Impairment loss	$ 0	0	0
Impact on adoption of ASU 2015-03	The retrospective application of the adoption of ASU 2015-03 did not have an impact on the December 31, 2014 consolidated balance sheet as the Company did not have debt issuance costs at that date. The adoption resulted in the classification of approximately $3.5 million of debt issuance costs as a direct reduction of the Company’s long-term debt and revolving credit facility on the December 31, 2015 consolidated balance sheet.
Minimum threshold percentage of voting securities on acquisition for deemed liquidation event	50.00%
Maximum voting power percentage after consolidation merger or reorganization for deemed liquidation event	50.00%
Preferred stock conversion trading price | $ / shares	$ 8.00
Convertible preferred stock, terms of conversion	conversion (Written Call Option) on the underlying shares if after three years the stock trades at $8.00 for thirty trading days, and (v) conversion (Contingent Forward) on the underlying shares automatically at the ten year anniversary of the issue date.
Accretion expense recognized period	3 years
Largest amount of tax benefit	Greater than 50%
Provision for interest or penalties related to uncertain tax positions	$ 0	$ 0	$ 0
Dividend yield (%)	0.00%	0.00%	0.00%
Accounting Standards Update 2015-03 [Member]
Schedule Of Significant Accounting Policies [Line Items]
Debt issuance cost	$ 3,500,000	$ 0
Net Revenues [Member] | Customer Concentration Risk [Member]
Schedule Of Significant Accounting Policies [Line Items]
Percentage of revenue derived from	5.00%
Net Revenues [Member] | Customer Concentration Risk [Member] | Oncology Practice Clients [Member]
Schedule Of Significant Accounting Policies [Line Items]
Percentage of revenue derived from		10.10%	15.80%
Net Revenues [Member] | Customer Concentration Risk [Member] | Other Individual Clients [Member]
Schedule Of Significant Accounting Policies [Line Items]
Percentage of revenue derived from		10.00%	10.00%
Net Revenues [Member] | Florida [Member] | Customer Concentration Risk [Member]
Schedule Of Significant Accounting Policies [Line Items]
Percentage of revenue derived from	20.50%	25.80%	30.60%