CONDENSED CONSOLIDATED STATEMENTS OF CONDITION - (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	35,463,269	23,996,293
Common stock, shares outstanding	35,463,269	23,996,293