CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Statement of Stockholders' Equity [Abstract]
Issuance of common stock (in shares)	3,260	10,128
Issuance of common stock purchased under the employee stock purchase plan (in shares)	4,155	3,234
Forfeiture of common stock (in shares)	1,042	1,142
Cash dividends (in dollars per share)	$ 0.625	$ 0.575
Purchase of common stock (in shares)	53,710	88,164