CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Statement of Stockholders' Equity [Abstract]
Issuance of common stock (in shares)	2,844	8,466
Issuance of common stock purchased under the employee stock purchase plan (in shares)	2,048	2,052
Forfeiture of common stock (in shares)	682	868
Cash dividends (in dollars per share)	$ 0.625	$ 0.575
Purchase of common stock (in shares)	20,031	40,458