|
Stock-Based Compensation (Details 6) (Stock options, USD $)
|
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2012
|
Dec. 31, 2011
|
Dec. 31, 2010
|
|
|
Minimum
|
|||
| Black-Scholes option valuation model, assumptions | |||
| Risk-free interest rate (as a percent) | 0.82% | 1.08% | 1.64% |
| Volatility factor (as a percent) | 40.36% | 34.68% | 31.00% |
| Expected term of options | 5 years 10 months 24 days | 5 years 1 month 6 days | 6 years 1 month 6 days |
| Weighted-average grant-date fair value (in dollars per share) | $ 10.60 | $ 8.07 | $ 6.44 |
|
Maximum
|
|||
| Black-Scholes option valuation model, assumptions | |||
| Risk-free interest rate (as a percent) | 1.33% | 2.57% | 2.97% |
| Volatility factor (as a percent) | 41.12% | 38.92% | 32.73% |
| Expected term of options | 6 years | 6 years | 6 years 2 months 12 days |
| Weighted-average grant-date fair value (in dollars per share) | $ 13.70 | $ 14.42 | $ 9.11 |