CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Issuance of common stock for dividend reinvestment plan (in shares)	42,438	42,872	43,650
Dividends paid on common stock (in dollars per share)	$ 1.26	$ 1.20	$ 1.11
Purchase of common stock (in shares)	66,467	1,459,148	0
Net issuance of common stock under employee stock plan (in shares)	122,537	140,692	159,356
Common Stock Dividends (in shares)			719,515
Net issuance of common stock in connection with the acquisition of Diboll State Bancshares, Inc. (in shares)			5,534,925