CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
CURRENT ASSETS:
Accounts receivable, allowance	$ 9,887	$ 9,787
PROPERTY, EQUIPMENT AND FACILITIES - accumulated depreciation and amortization	124,192	123,324
OTHER ASSETS :
Noncurrent receivables, allowance	$ 765	$ 837
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)	30,685,017	29,727,555
Common stock, shares outstanding (in shares)	30,685,017	29,727,555
Treasury stock, shares (in shares)	5,910,541	5,910,541