Summary of Stock Options Outstanding (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Options Outstanding
Number of options	10,379,668	8,228,334
Weighted average exercise price per share	$ 10.83	$ 10.20
Aggregate intrinsic value (in 000's)	$ 11,240
Weighted average remaining contractual term (years)	6 years 11 months 23 days
Options Exercisable
Number of options	4,489,008
Weighted average exercise price per share	$ 7.86
Aggregate intrinsic value (in 000's)	6,886
Weighted average remaining contractual term (years)	4 years 2 months 5 days
Options vested and expected to vest
Number of options	10,188,693
Weighted average exercise price per share	$ 10.73
Aggregate intrinsic value (in 000's)	$ 11,217
Weighted average remaining contractual term (years)	6 years 11 months 9 days