CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 1,715	$ 3,837
Shareholders' equity:
Preferred stock, authorized (in shares)	1,000,000	1,000,000
Preferred stock, issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.1	$ 0.1
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	47,555,927	47,002,939
Common stock held in treasury, shares (in shares)	13,205,741	12,053,319