Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 460	$ 397
Shareholders' equity:
Undesignated preferred stock, shares authorized (in shares)	5,000	5,000
Undesignated preferred stock, shares issued (in shares)	0	0
Undesignated preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	142,500	142,500
Common stock, shares issued (in shares)	56,705	56,397
Common stock, shares outstanding (in shares)	56,705	56,397