Note 11. Repurchases of common STOCK

The following is a summary of our open market common stock repurchases for the three and nine months ended September 30, 2013 and 2012 (in thousands, except per share amounts):


	For the Three Months Ended				For the Nine Months Ended
	September 30,				September 30,
	2013		2012		2013		2012

Shares repurchased		801		386		3,139		1,038
Total cost of shares repurchased	$	76,575	$	36,146	$	282,910	$	91,152
Average cost per share	$	95.52	$	93.76	$	90.12	$	87.82

We primarily acquire shares by means of repurchases in the open market. However, we also acquire shares that are surrendered by employees in payment for the minimum required withholding taxes due on the vesting of restricted stock units and the settlement of deferred stock units. The number of shares acquired through employee surrenders during both the three months ended September 30, 2013 and 2012 was not material. We acquired 47,483 shares having a total cost of $4.3 million in connection with such employee surrenders during the nine months ended September 30, 2013 compared to 51,484 shares having a total cost of $4.5 million during the nine months ended September 30, 2012.

We issue shares of treasury stock upon the vesting of certain restricted stock units and upon the exercise of certain stock options. The number of shares of treasury stock issued during both the nine months ended September 30, 2013 and 2012 was not material.