Summary of Restricted Stock Units Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock Units, Balance as of January 1	2,282	[1],[2]	2,317	[1]	3,283	[1]
Granted	602	[1]	221	[1]	263	[1]
Vested and released	(1,382)	[1]	(832)	[1]	(950)	[1]
Cancelled	(284)	[1]	(137)	[1]	(279)	[1]
Adjustments due to the spin-off			725	[1],[3]
Vested and released - post spin-off			(12)	[1]
Restricted Stock Units, Balance as of December 31	1,218	[1]	2,282	[1],[2]	2,317	[1]
Weighted Average Grant-Date Fair Value, Balance as of January 1	$ 21.47	[1],[2]	$ 40.24	[1]	$ 39.00	[1]
Granted	$ 32.07	[1]	$ 52.35	[1]	$ 52.42	[1]
Vested and released	$ 21.02	[1]	$ 39.32	[1]	$ 34.58	[1]
Cancelled	$ 22.82	[1]	$ 41.98	[1]	$ 41.76	[1]
Vested and released - post spin-off			$ 13.45	[1]
Weighted Average Grant-Date Fair Value, Balance as of December 31	$ 29.57	[1]	$ 21.47	[1],[2]	$ 40.24	[1]

[1] Reflects the one-for-two reverse stock split on December 20, 2011.

[2] Outstanding RSUs as of December 31, 2011 represent RSUs outstanding after giving effect to one-for-two reverse stock split and spin-off adjustments made in order to maintain the fair value of those awards immediately prior to and immediately following the transaction.

[3] Reflects the equitable adjustment to the number of unvested RSUs necessary to maintain the fair value of those awards immediately prior to and following the spin-off.