Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Accounts receivable, allowances	$ 397	$ 377
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	27,017,824	27,017,824
Treasury stock, shares	10,839,093	8,014,004
Stock trusts, shares	0	3,264,651