Percentage of Revenue by Geographic Area (Detail) - Geographic Concentration Risk - Total Revenue	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Concentration Risk [Line Items]
Revenues, percentage by country	100.00%	100.00%
United States
Concentration Risk [Line Items]
Revenues, percentage by country	38.00%	30.00%
Sweden
Concentration Risk [Line Items]
Revenues, percentage by country	27.00%	24.00%
Ireland
Concentration Risk [Line Items]
Revenues, percentage by country	10.00%	4.00%
United Kingdom
Concentration Risk [Line Items]
Revenues, percentage by country	5.00%	13.00%
Other
Concentration Risk [Line Items]
Revenues, percentage by country	20.00%	29.00%