CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, allowance for losses	$ 4,780	$ 5,427
Preferred stock, par value (usd per share)	$ 10.00	$ 10.00
Preferred stock, shares authorized (shares)	1,000,000	1,000,000
Preferred stock, shares issued (shares)	0	0
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	100,000,000	100,000,000
Common stock, shares issued (shares)	48,147,969	48,147,969
Common stock, shares outstanding (shares)	48,147,969	48,147,969
Treasury stock, shares (shares)	9,900,041	10,262,182