CONSOLIDATED BALANCE SHEETS (Parenthetical)	Mar. 31, 2012	Dec. 31, 2011
CONSOLIDATED BALANCE SHEETS
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	76,224,131	75,833,696
Treasury stock, shares	25,279,790	25,221,481