Percentage of Revenue by Geographic Area (Detail) - Geographic Concentration Risk - Total Revenue	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Concentration Risk [Line Items]
Revenues, percentage by country	100.00%	100.00%	100.00%	100.00%
Sweden
Concentration Risk [Line Items]
Revenues, percentage by country	27.00%	30.00%	39.00%	40.00%
United States
Concentration Risk [Line Items]
Revenues, percentage by country	38.00%	38.00%	29.00%	34.00%
United Kingdom
Concentration Risk [Line Items]
Revenues, percentage by country	18.00%	23.00%	18.00%	22.00%
Other
Concentration Risk [Line Items]
Revenues, percentage by country	17.00%	9.00%	14.00%	4.00%