Segments and Geographic Information - Additional Information (Detail)	3 Months Ended		12 Months Ended
	Mar. 31, 2018 Segment Customer	Mar. 31, 2017 Customer	Dec. 31, 2017 Customer
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments | Segment	2
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Service [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Additional customers accounted for 10% or more of total revenues	0	0
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Service [Member] | Customer One [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage	33.00%	17.00%
Customer Concentration Risk [Member] | Merck KGaA [Member] | Sales Revenue, Net [Member] | Product Segment [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage	100.00%	100.00%
Customer Concentration Risk [Member] | Merck KGaA [Member] | Accounts Receivable [Member] | Product Segment [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage	100.00%		100.00%
Credit Concentration Risk [Member] | Accounts Receivable [Member] | Service [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of customers	1		1
Credit Concentration Risk [Member] | Accounts Receivable [Member] | Service [Member] | Customer One [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage	44.00%		53.00%