Segment Reporting (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Product revenues	$ 240,056	$ 261,504	$ 741,303	$ 792,490
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
United States
Segment Reporting Information [Line Items]
Product revenues	$ 111,570	$ 125,936	$ 340,656	$ 369,798
Germany
Segment Reporting Information [Line Items]
Product revenues	20,379	22,681	63,889	68,670
Japan
Segment Reporting Information [Line Items]
Product revenues	20,508	16,672	59,102	43,520
China
Segment Reporting Information [Line Items]
Product revenues	17,591	22,756	49,598	71,887
South Korea
Segment Reporting Information [Line Items]
Product revenues	14,543	12,814	45,098	42,419
Czech Republic
Segment Reporting Information [Line Items]
Product revenues	8,805	10,742	30,956	33,563
Canada
Segment Reporting Information [Line Items]
Product revenues	8,833	7,778	29,226	33,482
United Kingdom
Segment Reporting Information [Line Items]
Product revenues	8,315	9,037	23,980	28,349
Other
Segment Reporting Information [Line Items]
Product revenues	29,512	33,088	98,798	100,802
Non U.S.
Segment Reporting Information [Line Items]
Product revenues	$ 128,486	$ 135,568	$ 400,647	$ 422,692