Stockholders' Equity - Activity Under Stock Option Plans (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Number of Shares Underlying Stock Options
Outstanding beginning balance (shares)	6,190
Granted (shares)	0
Exercised (shares)	(2,844)
Cancelled or expired (shares)	(70)
Outstanding ending balance (shares)	3,276
Vested and expected to vest at December 31, 2012 (shares)	3,252
Exercisable at December 31, 2012 (shares)	2,733
Weighted Average Exercise Price per Share
Outstanding beginning balance (usd per share)	$ 14.23
Granted (usd per share)	$ 0.00
Exercised (usd per share)	$ 13.03
Cancelled or expired (usd per share)	$ 17.14
Outstanding ending balance (usd per share)	$ 15.21
Vested and expected to vest at December 31, 2012 (usd per share)	$ 15.18
Exercisable at December 31, 2012 (usd per share)	$ 14.62
Weighted Average Remaining Contractual Term (in years)
Outstanding as of December 31, 2012	4 years 3 months 15 days
Vested and expected to vest at December 31, 2012	4 years 3 months 11 days
Exercisable at December 31, 2012	4 years 2 months 12 days
Aggregate Intrinsic Value
Outstanding as of December 31, 2012	$ 41,088
Vested and expected to vest at December 31, 2012	40,876
Exercisable at December 31, 2012	$ 35,903

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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