Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Consolidated Balance Sheets
Receivables, allowance for doubtful accounts	$ 11,443	$ 12,187
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	160,000,000	160,000,000
Common stock, shares issued	95,065,638	95,065,638
Common stock, shares outstanding	58,182,157	58,638,863
Treasury stock, shares	36,883,481	36,426,775