Stock-Based Compensation - Company's Activities with Respect to its Stock Options (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, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares Outstanding, Beginning Balance	3,608	3,786	4,196
Number of Shares, Granted	613	578	539
Number of Shares, Exercised	(1,381)	(704)	(889)
Number of Shares, Canceled	(9)	(52)	(60)
Number of Shares Outstanding, Ending Balance	2,831	3,608	3,786
Weighted-Average Exercise Price Per Share Outstanding, Beginning Balance	$ 28.06	$ 24.78	$ 21.77
Number of Shares Exercisable, at December 31, 2012	1,305
Weighted-Average Exercise Price Per Share, Granted	$ 47.58	$ 41.91	$ 35.64
Number of Shares Unvested, at December 31, 2012	1,526
Weighted-Average Exercise Price Per Share, Exercised	$ 24.37	$ 21.53	$ 17.01
Weighted-Average Exercise Price Per Share, Canceled	$ 37.71	$ 32.07	$ 26.71
Weighted-Average Exercise Price Per Share Outstanding, Ending Balance	$ 34.06	$ 28.06	$ 24.78
Weighted-Average Remaining Contractual Life (in Years) Outstanding, at December 31, 2012	4 years 1 month 6 days
Weighted-Average Exercise Price Per Share Exercisable, at December 31, 2012	$ 27.66
Weighted-Average Remaining Contractual Life (in years) Exercisable, at December 31, 2012	2 years 10 months 24 days
Weighted-Average Exercise Price Per Share Unvested, at December 31, 2012	$ 39.53
Weighted-Average Remaining Contractual Life (in years) Unvested, at December 31, 2012	5 years 1 month 6 days
Aggregate Intrinsic Value Outstanding, at December 31, 2012	$ 104,549
Aggregate Intrinsic Value Exercisable, at December 31, 2012	56,545
Aggregate Intrinsic Value Outstanding, Unvested at December 31, 2012	$ 48,004