Business Segment, Geographic Areas and Major Customers - Product Sales by Geographic Location (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, net	$ 70,021	$ 66,472
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, net	42,189	33,788
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, net	12,741	14,678
International, Excluding Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, net	$ 15,091	$ 18,006