Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - shares	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Common stock, shares issued	17,459,961	17,459,961	17,459,961	17,459,961
Treasury stock, shares	2,049,797	1,915,884	1,405,638	693,769