Fully Vested Stock Options (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Vested stock options, Shares	3,757,099	[1],[2],[3]	279,750	[1],[2],[3]	326,574	[1],[2],[3]
Vested stock options, Weighted average exercise price	$ 2.07	[1],[2],[3]	$ 1.30	[1],[2],[3]	$ 1.30	[1],[2],[3]

[1] The weighted average contractual term of fully vested options is 7.04 years, 7.85 years and 8.75 years as of December 31, 2013, 2012 and 2011, respectively.

[2] The fair value of vested stock options at December 31, 2013, 2012 and 2011 amounted to $92.7 million, $2.0 million and $2.8 million, respectively.

[3] At December 31, 2013, 2012 and 2011, the aggregate intrinsic value amounted to $84.9 million, $1.6 million and $1.2 million, respectively.