Nature of Business and Basis of Presentation - Additional Information (Detail)	1 Months Ended	6 Months Ended
Sep. 30, 2018 Employee	Jun. 30, 2019 USD ($) Patient Employee Segment	Dec. 31, 2018 USD ($)
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
REDUCE-IT study, number of patients enrolled and randomized \| Patient		8,179
Number of sales professionals \| Employee		800
Number of operating segments \| Segment		1
Total current assets		$ 372,043,000	$ 377,997,000
Cash and cash equivalents		221,771,000	249,227,000
Accounts receivable, net		95,398,000	66,523,000
Inventory		46,268,000	$ 57,802,000
Other debt outstanding		$ 0
Sales Representatives and Managers
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of sales professionals \| Employee	170	440
Sales Representatives
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of sales professionals \| Employee		400

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