CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (UNAUDITED) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Stockholders' Equity [Abstract]
Cash dividends declared (in dollars per share)	$ 0.26	$ 0.26
Distribution of shares of treasury stock for directors' compensation (in shares)	6,015	7,880
Distribution of shares of treasury stock for employee stock compensation (in shares)	1,784	5,861
Sale of shares of treasury stock (in shares)	2,648	6,101
Restricted stock awards, forfeited (in shares)		1,139