CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Statement Of Stockholders Equity [Abstract]
Common stock dividends, per share	$ 0.44	$ 0.36
Stock option plan, shares	26,695	13,721
Employee stock purchase plan, shares	12,613	11,423
Director stock purchase plan, shares	837
Restricted stock, shares	52,921	54,535
Treasury Stock, Shares, Acquired	575,472