|
Share-based Compensation Plans and Awards - Employee Stock Purchase Plan (Details) (USD $)
In Thousands, except Share data, unless otherwise specified |
3 Months Ended | 6 Months Ended | 9 Months Ended | 1 Months Ended | 3 Months Ended | 9 Months Ended | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Sep. 30, 2012
|
Jun. 30, 2011
|
Jun. 30, 2011
|
Sep. 30, 2012
|
May 31, 2011
Employee Stock Purchase Plan [Member]
|
Sep. 30, 2012
Employee Stock Purchase Plan [Member]
|
Sep. 30, 2012
Employee Stock Purchase Plan [Member]
period
|
Sep. 30, 2012
Employee Stock Purchase Plan [Member]
Period one [Member]
period
|
Sep. 30, 2012
Employee Stock Purchase Plan [Member]
Period two [Member]
period
|
Sep. 30, 2012
Employee Stock Purchase Plan [Member]
Period three [Member]
period
|
Sep. 30, 2012
Employee Stock Purchase Plan [Member]
Period four [Member]
period
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||||||||
| Share-based compensation arrangement by share-based payment award, discount from market price, lower of purchase and offer date | 15.00% | ||||||||||
| Participants maximum payroll deductions percentage | 15.00% | ||||||||||
| Number of concurrent offering periods | 4 | ||||||||||
| Duration of each offering period | 24 months | 18 months | 12 months | 6 months | |||||||
| Number of purchase periods in each offering period | 4 | 3 | 2 | 1 | |||||||
| Duration of each purchase period | 6 months | ||||||||||
| Maximum number of common stock shares may be purchased by each participant | 1,250 | ||||||||||
| Duration of each interval in each purchase period within an offering | 6 months | ||||||||||
| Fair value assumptions, expected life | 24 months | ||||||||||
| Fair value assumptions, expected volatility, minimum | 34.00% | ||||||||||
| Fair value assumptions, expected volatility, maximum | 43.00% | ||||||||||
| Stock-based compensation expense | $ 8,046 | $ 7,755 | $ 22,102 | $ 23,986 | $ 0 | $ 1 | |||||
| Number of common stock shares remaining authorized for issuance | 9,535,000 | 9,535,000 | |||||||||
| Unrecognized compensation cost | $ 2 | $ 2 | |||||||||