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Stock-Based Compensation (Details) 2 (USD $)
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3 Months Ended | 1 Months Ended | |||
|---|---|---|---|---|---|
|
Mar. 31, 2013
Stock Options
|
Mar. 31, 2012
Stock Options
|
Jul. 31, 2012
LTIP Plan
|
Mar. 31, 2013
LTIP Plan
|
Mar. 31, 2013
Assumed Plans
|
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||
| Incremental number of shares authorized | 5,000,000 | ||||
| Maximum common shares issued under plan | 1,492,014 | ||||
| Stock-based awards available for grant | 6,772,362 | 980,090 | |||
| Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] | |||||
| Total stock options granted | 365,080 | 368,840 | |||
| Volatility | 45.40% | 49.20% | |||
| Risk-free interest rate | 0.81% | 0.83% | |||
| Expected life (in years) | 4 years 6 months | 4 years 6 months | |||
| Dividend yield | 0.00% | 0.00% | |||
| Weighted-average grant date fair value (in dollars per share) | $ 21.44 | $ 14.45 | |||