CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
Cash dividends, common stock (in dollars per share)	$ 0.40	$ 0.36
Stock dividends, restricted stock units (in dollars per share)	$ 0.40	0.36
Stock dividends, accrued restricted stock awards (in dollars per share)		$ 0.36
Return of equity trust shares		28,648