Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Accounts receivable, allowance for losses	$ 1,640	$ 1,725
Preferred stock, par value	$ 10.00	$ 10.00
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	48,147,969	48,147,969
Treasury stock, shares	11,373,666	14,678,782