Stockholders' Equity (Deficiency) - Options Outstanding Separated into Range of Exercise Price (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding	3,715,652	3,233,235
Options outstanding, Weighted average remaining contractual life	5 years 9 months 27 days
Options outstanding, Weighted average exercise price	$ 7.493	$ 4.033
Options exercisable	2,682,549
Options exercisable, Weighted average remaining contractual life	4 years 6 months 3 days
Options exercisable, Weighted average exercise price	$ 1.948
$0.070-0.901 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise price, Lower limit	$ 0.070
Range of exercise price, Upper limit	$ 0.901
Options outstanding	758,047
Options outstanding, Weighted average remaining contractual life	2 years 10 months 14 days
Options outstanding, Weighted average exercise price	$ 0.744
Options exercisable	758,047
Options exercisable, Weighted average remaining contractual life	2 years 10 months 14 days
Options exercisable, Weighted average exercise price	$ 0.744
$1.039-1.576 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise price, Lower limit	$ 1.039
Range of exercise price, Upper limit	$ 1.576
Options outstanding	1,671,942
Options outstanding, Weighted average remaining contractual life	4 years 8 months 16 days
Options outstanding, Weighted average exercise price	$ 1.260
Options exercisable	1,663,059
Options exercisable, Weighted average remaining contractual life	4 years 8 months 13 days
Options exercisable, Weighted average exercise price	$ 1.258
$6.230-8.800 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise price, Lower limit	$ 6.230
Range of exercise price, Upper limit	$ 8.800
Options outstanding	180,773
Options outstanding, Weighted average remaining contractual life	7 years 4 months 18 days
Options outstanding, Weighted average exercise price	$ 6.713
Options exercisable	121,081
Options exercisable, Weighted average remaining contractual life	7 years 3 months 19 days
Options exercisable, Weighted average exercise price	$ 6.758
$12.470 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise price, Upper limit	$ 12.470
Options outstanding	433,950
Options outstanding, Weighted average remaining contractual life	8 years 8 months 4 days
Options outstanding, Weighted average exercise price	$ 12.470
Options exercisable	140,362
Options exercisable, Weighted average remaining contractual life	8 years 7 months 22 days
Options exercisable, Weighted average exercise price	$ 12.470
$21.14-24.23 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise price, Lower limit	$ 21.140
Range of exercise price, Upper limit	$ 24.230
Options outstanding	459,090
Options outstanding, Weighted average remaining contractual life	9 years 7 months 21 days
Options outstanding, Weighted average exercise price	$ 22.000
$39.86 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise price, Upper limit	$ 39.860
Options outstanding	211,850
Options outstanding, Weighted average remaining contractual life	9 years 8 months 24 days
Options outstanding, Weighted average exercise price	$ 39.860