Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Common stock, par or stated value per share (in dollars per share)	$ 0.01	$ 0.01
Stock issued for benefit plans (shares)	50,987	37,068
Options exercised, shares	36,415	130,902
Purchase of treasury shares (shares)	80,652	80,014
Employee stock purchase plan (shares)	42,624	49,089
Issuance of restricted stock (shares)	349,766	348,972