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Stock-Based Compensation (Details 6) (Stock options, USD $)
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12 Months Ended | ||
|---|---|---|---|
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Dec. 31, 2013
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Dec. 31, 2012
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Dec. 31, 2011
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| Black-Scholes option valuation model assumptions | |||
| Dividend yield percentage | 0.00% | ||
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Minimum
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|||
| Black-Scholes option valuation model assumptions | |||
| Risk-free interest rate (as a percent) | 0.99% | 0.82% | 1.08% |
| Volatility factor (as a percent) | 37.54% | 40.36% | 34.68% |
| Expected term of options | 5 years 4 months 24 days | 5 years 10 months 24 days | 5 years 1 month 6 days |
| Weighted-average grant-date fair value (in dollars per share) | $ 15.59 | $ 10.60 | $ 8.07 |
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Maximum
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|||
| Black-Scholes option valuation model assumptions | |||
| Risk-free interest rate (as a percent) | 1.54% | 1.33% | 2.57% |
| Volatility factor (as a percent) | 42.23% | 41.12% | 38.92% |
| Expected term of options | 5 years 6 months | 6 years | 6 years |
| Weighted-average grant-date fair value (in dollars per share) | $ 17.20 | $ 13.70 | $ 14.42 |