Condensed Consolidated Statements of Stockholders' Equity (Parenthetical)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Stock issued for benefit plans (shares)	50,987	37,068
Options exercised, shares	19,077	130,902
Purchase of treasury shares (shares)	78,758	80,014
Employee stock purchase plan (shares)	42,624	49,089
Common Stock
Options exercised, shares		130,902
Employee stock purchase plan (shares)		49,089
Issuance of restricted stock (shares)	309,816	348,972
Treasury Stock
Stock issued for benefit plans (shares)	50,987	37,068
Purchase of treasury shares (shares)	78,758	80,014
Additional Paid-in Capital
Stock issued for benefit plans (shares)	50,987	37,068
Options exercised, shares	19,077	130,902
Employee stock purchase plan (shares)	42,624	49,089
Issuance of restricted stock (shares)	309,816	348,972