Summary of Significant Accounting Policies - Schedule of Customer and Product Concentration Risk (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts Receivable | Customer Concentration Risk | Company B
Concentration Risk [Line Items]
Concentration risk percentage	14.50%	13.10%
Accounts Receivable | Customer Concentration Risk | Company C
Concentration Risk [Line Items]
Concentration risk percentage		10.50%
Revenues | Customer Concentration Risk | Company A
Concentration Risk [Line Items]
Concentration risk percentage	12.00%	10.30%	11.30%
Revenues | Customer Concentration Risk | Company B
Concentration Risk [Line Items]
Concentration risk percentage	10.40%	11.40%	11.90%
Revenues | Customer Concentration Risk | Company C
Concentration Risk [Line Items]
Concentration risk percentage	10.30%
Net Product Revenue | Product Concentration Risk | DEFINITY
Concentration Risk [Line Items]
Concentration risk percentage	47.50%	43.60%	38.10%
Net Product Revenue | Product Concentration Risk | TechneLite
Concentration Risk [Line Items]
Concentration risk percentage	31.60%	32.90%	24.70%
Net Product Revenue | Product Concentration Risk | Xenon
Concentration Risk [Line Items]
Concentration risk percentage			16.70%