Stockholders' Equity (Details 3)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of the number of shares outstanding with the number of shares used in computing basic and diluted earnings per share
Common shares outstanding, end of period	37,069,000	37,050,000	37,532,000
Effect of using weighted average common shares outstanding	43,000	339,000	17,000
Shares used in computing earnings per share - basic	37,112,000	37,389,000	37,549,000
Effect of shares issuable under stock option plans based on the treasury stock method	87,000		241,000
Effect of contingently issuable restricted shares	60,000
Shares used in computing earnings per share - diluted	37,259,000	37,389,000	37,790,000
Number of shares of unvested contingently issuable restricted stock outstanding	200,000	400,000	400,000