CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - UNAUDITED - (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Stockholders Equity [Abstract]
Common stock dividends, per share	$ 0.30	$ 0.30	$ 0.60	$ 0.58
Revere Bank acquisition	12,768,949		12,768,949
Stock option plan, shares	2,625	4,142	8,638	10,897
Conversion of Revere stock options	395,298		395,298
Employee stock purchase plan, shares	20,198	10,004	28,815	17,666
Restricted stock, shares	44,578	42,830	44,578	54,789
Director stock purchase plan, shares		867		867
Treasury stock purchased			820,328