|
Stock-Based Compensation (Details 2) (USD $)
|
3 Months Ended | 1 Months Ended | 3 Months Ended |
|---|---|---|---|
|
Mar. 31, 2012
Restricted stock awards
|
Feb. 29, 2008
Restricted stock awards
Executive Management
|
Mar. 31, 2012
Performance share awards
|
|
| Stock-based compensation | |||
| Vesting period (in years) of shares awarded in 2008 | 3 years | 5 years | 3 years |
| Award Activity | |||
| Shares granted | 11,298 | 56,700 | |
| Performance share awards | |||
| Shares granted (in dollars per share) | $ 69.76 | ||
| Weighted average grant date fair value (in dollars per share) | $ 49.56 |