XML 39 R31.htm IDEA: XBRL DOCUMENT  v2.3.0.11
Income Taxes (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2011
Jun. 30, 2010
Jun. 30, 2011
Jun. 30, 2010
Income Taxes        
Income tax provision $ 11,049 $ 7,765 $ 21,464 $ 15,446
Effective income tax rate (as a percent) 17.90% 17.30% 18.90% 17.90%