Segment Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			2
Geographical revenues
Revenues	$ 66,010	$ 85,705	$ 156,714	$ 172,215
Operating (loss) income	(5,545)	14,537	1,580	30,706
Interest expense	1,914	4,543	3,860	9,135
Loss on extinguishment of debt	0	3,196	0	3,196
Other income	(756)	(1,312)	(1,106)	(2,499)
(Loss) income before income taxes	(6,703)	8,110	(1,174)	20,874
DEFINITY
Geographical revenues
Revenues	40,365	54,629	97,156	105,740
TechneLite
Geographical revenues
Revenues	18,909	20,106	42,007	44,251
Other nuclear
Geographical revenues
Revenues	10,277	15,246	25,777	30,366
Rebates and allowances
Geographical revenues
Revenues	3,541	4,276	8,226	8,142
U.S.
Geographical revenues
Revenues	57,399	75,190	136,144	150,624
Operating (loss) income	(6,001)	12,689	(1,013)	27,273
U.S. | DEFINITY
Geographical revenues
Revenues	39,544	53,466	94,554	103,182
U.S. | TechneLite
Geographical revenues
Revenues	15,591	16,865	34,947	36,923
U.S. | Other nuclear
Geographical revenues
Revenues	5,804	9,127	14,866	18,651
U.S. | Rebates and allowances
Geographical revenues
Revenues	3,540	4,268	8,223	8,132
International
Geographical revenues
Revenues	8,611	10,515	20,570	21,591
Operating (loss) income	456	1,848	2,593	3,433
International | DEFINITY
Geographical revenues
Revenues	821	1,163	2,602	2,558
International | TechneLite
Geographical revenues
Revenues	3,318	3,241	7,060	7,328
International | Other nuclear
Geographical revenues
Revenues	4,473	6,119	10,911	11,715
International | Rebates and allowances
Geographical revenues
Revenues	$ 1	$ 8	$ 3	$ 10