Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation (Details)

v2.4.0.6
Share-Based Compensation (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
1997 Plan and 2003 Plan [Member]
Y
Dec. 31, 2011
1997 Plan and 2003 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Total share-based compensation expense recognized $ 1.9 $ 6.3 $ 4.2 $ 14.4    
Total unrecognized compensation cost related to non-vested share-based compensation         $ 7.4 $ 7.7
Recognition period for total unrecognized compensation expense         4  
Weighted average recognition period on unrecognized compensation expense         2.4