Summary of Stock Options Outstanding (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding Number of shares	1,814
Outstanding Weighted average remaining contractual life (in years)	7 years 5 months 19 days
Outstanding Weighted average exercise price	$ 5.65
Exercisable Number of shares	874
Exercisable Weighted average exercise price	$ 9.28
Range 1
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, minimum	$ 0.00
Range of exercise prices, maximum	$ 10.00
Outstanding Number of shares	1,502
Outstanding Weighted average remaining contractual life (in years)	8 years 4 months 24 days
Outstanding Weighted average exercise price	$ 2.55
Exercisable Number of shares	569
Exercisable Weighted average exercise price	$ 3.30
Range 2
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, minimum	$ 10.01
Range of exercise prices, maximum	$ 20.00
Outstanding Number of shares	161
Outstanding Weighted average remaining contractual life (in years)	2 years 10 months 13 days
Outstanding Weighted average exercise price	$ 16.16
Exercisable Number of shares	161
Exercisable Weighted average exercise price	$ 16.15
Range 3
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, minimum	$ 20.01
Range of exercise prices, maximum	$ 30.00
Outstanding Number of shares	128
Outstanding Weighted average remaining contractual life (in years)	3 years 7 months 10 days
Outstanding Weighted average exercise price	$ 23.61
Exercisable Number of shares	121
Exercisable Weighted average exercise price	$ 23.71
Range 4
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, minimum	$ 30.01
Range of exercise prices, maximum	$ 41.25
Outstanding Number of shares	23
Outstanding Weighted average remaining contractual life (in years)	9 months 25 days
Outstanding Weighted average exercise price	$ 33.32
Exercisable Number of shares	23
Exercisable Weighted average exercise price	$ 33.32