Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2012

Share Repurchases [Abstract]

Schedule of Share Repurchases [Table Text Block]

Share repurchases were as follows:

	Years Ended December 31,
	2012		2011		2010
Shares repurchased in the open market	12,314,795		4,034,973		2,335,500
Shares repurchased from holders of employee stock options	86,303		80,166		82,455
Total shares repurchased	12,401,098		4,115,139		2,417,955
Average price paid per share	$	60.38	$	58.93	$	51.10