Consolidated Statements of Financial Condition (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	5,090,901	4,876,104
Common stock, shares outstanding	5,080,857	4,809,594
Treasury stock, shares	10,044	66,510