STOCK-BASED COMPENSATION - PERFORMANCE STOCK AWARDS (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011 Years	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected Forfeiture Rate Employees	5.00%
Expected Forfeiture Rates, Executives Directors	4.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Shares Forfeited, Weighted Average Exercise Price	$ (6.49)
Total Unrecognized Compensation Cost	$ 0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected Forfeiture Rate Employees	5.00%
Expected Forfeiture Rates, Executives Directors	4.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Number of Shares, Unvested at beginning of period	161,618
Number of Shares, Granted	205,671
Number of Shares, Vested	(58,238)
Number of Shares, Unvested at end of period	309,051	161,618
Shares, Unvested, Weighted Average Grant Date Fair Value, beginning of period	$ 29.03
Shares Granted, Weighted Average Grant Date Fair Value	$ 50.67
Shares Vested, Weighted Average Grant Date Fair Value	$ 29.39
Shares, Unvested, Weighted Average Grant Date Fair Value, end of period	$ 43.36	$ 29.03
Total Unrecognized Compensation Cost	10.60
Expected to be Recognized over a Weighted Average Period	4.0
Total Fair Value, Vested in period	3.7	1.4	0.7
Performance Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance Evaluation Stock-Based Compensation		2	2
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Number of Shares, Unvested at beginning of period	307,510
Number of Shares, Granted	73,499
Number of Shares, Vested	(263,386)
Number of Shares, Forfeited	(4,700)
Number of Shares, Unvested at end of period	112,923	307,510
Shares, Unvested, Weighted Average Grant Date Fair Value, beginning of period	$ 25.60
Shares Granted, Weighted Average Grant Date Fair Value	$ 50.87
Shares Vested, Weighted Average Grant Date Fair Value	$ 26.03
Shares Forfeited, Weighted Average Exercise Price	$ 25.00
Shares, Unvested, Weighted Average Grant Date Fair Value, end of period	$ 41.09	$ 25.60
Total Unrecognized Compensation Cost	1.90
Total Fair Value, Vested in period	$ 16.8	$ 0.6	$ 1.1

Performance Evaluation Stock-Based Compensation

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Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Forfeiture Rate Employees

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Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Forfeiture Rates, Executives Directors

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- 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.

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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.

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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).

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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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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.

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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-Paragraph A240

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The combined weighted average exercise price associated with stock options during the period that have either lapsed or been forfeited.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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