CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
CURRENT ASSETS:
Accounts receivable, allowance	$ 8,407	$ 9,297
PROPERTY, EQUIPMENT AND FACILITIES - accumulated depreciation and amortization	126,877	122,037
OTHER ASSETS :
Noncurrent receivables, allowance	$ 742	$ 821
STOCKHOLDERS' EQUITY:
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	30,768,433	29,727,555
Common stock, shares outstanding (in shares)	30,768,433	29,727,555
Treasury stock, shares (in shares)	5,910,541	5,910,541