Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	20,555,330	20,555,330
Deferred compensation trust, shares	108,640	108,614
Treasury stock, shares	16,862,327	16,664,342