Summary of Stock Option 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]
Options, Balance as of January 1	14,798	[1],[2]	9,103	[1]	9,001	[1]
Options, Granted	5,586	[1]	3,725	[1]	2,908	[1]
Options, Exercised	(3,582)	[1]	(1,176)	[1]	(1,834)	[1]
Options, Cancelled	(1,566)	[1]	(1,030)	[1]	(972)	[1]
Options, Adjustments due to the spin-off			4,288	[1],[3]
Options, Exercised - post spin-off			(112)	[1]
Options, Balance as of December 31	15,236	[1]	14,798	[1],[2]	9,103	[1]
Weighted Average Exercise Price, January 1	$ 17.96	[1],[2]	$ 35.90	[1]	$ 30.34	[1]
Options, Exercisable as of December 31, 2012	4,080	[1]
Weighted Average Exercise Price, Granted	$ 36.36	[1]	$ 43.19	[1]	$ 52.42	[1]
Options, Vested and expected to vest after December 31, 2012	11,733	[1]
Weighted Average Exercise Price, Exercised	$ 13.31	[1]	$ 24.16	[1]	$ 24.96	[1]
Weighted Average Exercise Price, Cancelled	$ 23.47	[1]	$ 32.48	[1]	$ 30.96	[1]
Weighted Average Exercise Price, Exercised - post spin-off			$ 14.13	[1]
Weighted Average Exercise Price, December 31	$ 25.24	[1]	$ 17.96	[1],[2]	$ 35.90	[1]
Weighted Average Exercise Price, Exercisable as of December 31, 2012	$ 22.15	[1]
Weighted Average Exercise Price, Vested and expected to vest after December 31, 2012	$ 23.65	[1]
Remaining Contractual Life (In years), Balance as of December 31, 2012	4 years 9 months 18 days
Remaining Contractual Life (In years), Exercisable as of December 31, 2012	3 years 2 months 12 days
Remaining Contractual Life (In years), Vested and expected to vest after December 31, 2012	4 years 10 months 24 days
Aggregate intrinsic value, Balance as of December 31, 2012	$ 551,510
Aggregate intrinsic value, Exercisable as of December 31, 2012	160,295
Aggregate intrinsic value, Vested and expected to vest after December 31, 2012	$ 443,386

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

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

[3] Reflects the equitable adjustment to the exercise prices and number of outstanding stock options necessary to maintain the intrinsic value of those awards immediately prior to and following the spin-off.