XML 98 R85.htm IDEA: XBRL DOCUMENT v2.4.0.6
Reconciliation of Number of Common Shares Used in Calculating Basic and Diluted Net Earnings Per Share (Detail) (USD $)
3 Months Ended 12 Months Ended
Dec. 31, 2011
Sep. 30, 2011
Jun. 30, 2011
Mar. 31, 2011
Dec. 31, 2010
Sep. 30, 2010
Jun. 30, 2010
Mar. 31, 2010
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]                      
Basic average common shares outstanding                 22,913,881 22,947,400 22,720,614
Incremental shares due to:                      
Restricted stock units                 220,457 356,048 601,432
Performance shares                 817,946 366,504 218,080
Diluted average common shares outstanding                 23,952,284 23,669,952 23,540,126
Basic net earnings per common share $ 0.51 $ 0.38 $ 0.60 $ 0.25 $ 1.65 $ 0.65 $ 0.90 $ 0.02 $ 1.73 $ 3.22 $ 8.03
Diluted net earnings per common share $ 0.48 $ 0.37 $ 0.59 $ 0.24 $ 1.60 $ 0.64 $ 0.87 $ 0.02 $ 1.66 $ 3.12 $ 7.75
Anti-dilutive shares excluded from calculation                 88,674   23,938