Percentage of Revenue by Geographic Area (Detail) - Geographic Concentration Risk - Total Revenue	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Concentration Risk [Line Items]
Revenues, percentage by country	100.00%	100.00%	100.00%	100.00%
United States
Concentration Risk [Line Items]
Revenues, percentage by country	45.00%	21.00%	37.00%	25.00%
Sweden
Concentration Risk [Line Items]
Revenues, percentage by country	29.00%	51.00%	31.00%	44.00%
United Kingdom
Concentration Risk [Line Items]
Revenues, percentage by country	6.00%	17.00%	10.00%	18.00%
Other
Concentration Risk [Line Items]
Revenues, percentage by country	20.00%	11.00%	22.00%	13.00%