Stock-Based Compensation Stock-Based Compensation Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified | 9 Months Ended | |||||
|---|---|---|---|---|---|---|
Sep. 30, 2011
years | Sep. 30, 2010 | |||||
Maximum [Member] | Long Term Performance Restricted Stock Award [Member] | ||||||
| [Line Items] | ||||||
| Maximum number of RSUs that may become eligible for vesting related to performance awards granted in the year | 133,000 | |||||
Stock Incentive Plan [Member] | ||||||
| [Line Items] | ||||||
| Number of shares authorized for issuance under the Stock Incentive Plan | 3,500,000 | |||||
| Number of shares available for future grant under the Stock Incentive Plan | 2,226,303 | |||||
Employee Stock Option [Member] | ||||||
| [Line Items] | ||||||
| Award vesting rights | Options generally become exercisable in three equal annual installments beginning one year from the date of grant | |||||
| Unrecognized compensation expense | $ 1.5 | |||||
| Unrecognized compensation expense, Expected weighted average period for recognition | 1.0 | |||||
| Stock Options Expiration Period | 10 | |||||
Restricted Stock Units (RSUs) [Member] | ||||||
| [Line Items] | ||||||
| Award vesting rights | Restricted stock units generally vest over a three year period. | |||||
| Unrecognized compensation expense | $ 21.8 | |||||
| Unrecognized compensation expense, Expected weighted average period for recognition | 2.0 | |||||
| Granted, Weighted Average Grant Date Fair Value | $ 54.82 | [1] | $ 63.42 | [1] | ||
Long Term Performance Restricted Stock Award [Member] | ||||||
| [Line Items] | ||||||
| Granted, Weighted Average Grant Date Fair Value | $ 56.73 | |||||
Employee Stock [Member] | ||||||
| [Line Items] | ||||||
| ESPP, percentage discount from market price on purchase date | 15.00% | |||||
| ESPP, maximum percentage of employee salary eligible for participation | 10.00% | |||||
| Shares available for future issuance under the ESPP | 131,000 | |||||
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| X | ||||||||||
- Definition The maximum number of the annual restricted awards that may become eligible for vesting pending the satisfaction of performance conditions.
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| X | ||||||||||
- Definition The number of shares of common stock available for future issuance under the employee stock purchase plan as of the balance sheet date.
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| X | ||||||||||
- Definition Stock Options Expiration Period in Years from Grant Date
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| X | ||||||||||
- Definition As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition The weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, using a decimal to express in number of years. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition The discount rate from market value on purchase date that participants pay for shares. 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 highest percentage of annual salary that an employee is permitted to utilize with respect to the plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- 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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