Stock-Based Compensation Restricted Stock Units Summary (Details) (Restricted Stock Units (RSUs) [Member], USD $) In Thousands, except Per Share data | 9 Months Ended | |||||||
|---|---|---|---|---|---|---|---|---|
Sep. 30, 2011 | Sep. 30, 2010 | |||||||
Restricted Stock Units (RSUs) [Member] | ||||||||
| [Line Items] | ||||||||
| Outstanding, beginning balance, Number | 588 | 326 | ||||||
| Granted, Number | 286 | [1] | 215 | [1] | ||||
| Granted, Weighted Average Grant Date Fair Value | $ 54.82 | [1] | $ 63.42 | [1] | ||||
| Released, Number | (201) | (78) | ||||||
| Released, Aggregate Intrinsic Value | $ 15,739 | [2] | $ 5,216 | [2] | ||||
| Forfeited, Number | (37) | (14) | ||||||
| Outstanding, ending balance, Number | 636 | 449 | ||||||
| Expected to vest, Number | 544 | |||||||
| Expected to vest, Aggregate Intrinsic Value | $ 16,040 | [2] | ||||||
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- Definition The aggregate intrinsic value of RSUs, as at the end of the period, expected to vest, is the market value of stock, before applicable income taxes, based on the closing price at the end of the period.
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| X | ||||||||||
- Definition Total number of restricted awards expected to vest as of the end of the reporting period.
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| X | ||||||||||
- Definition The aggregate instrinsic value for RSU's released is the market value of stock, before applicable income taxes, based on the closing price on the stock release date.
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| X | ||||||||||
- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
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- Definition Number of shares related to Restricted Stock Award forfeited during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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