For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Summary of Significant Accounting Policies - Concentration Risk (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Receivable \| Customer Concentration Risk \| Company A
Concentration Risk [Line Items]
Concentration risk percentage	11.00%	15.00%
Revenues \| Customer Concentration Risk \| Company A
Concentration Risk [Line Items]
Concentration risk percentage		12.00%	11.00%
Revenues \| Customer Concentration Risk \| Company B
Concentration Risk [Line Items]
Concentration risk percentage		10.00%	10.00%
Revenues \| Customer Concentration Risk \| Company C
Concentration Risk [Line Items]
Concentration risk percentage		10.00%
Revenues \| Product Concentration Risk \| DEFINITY
Concentration Risk [Line Items]
Concentration risk percentage	53.30%	47.50%	43.60%
Revenues \| Product Concentration Risk \| TechneLite
Concentration Risk [Line Items]
Concentration risk percentage	28.80%	31.60%	32.90%