Share-Based Employee Compensation Plans and Other Compensation and Benefit Plans (Employee Stock Purchase Plan Activity) (Details) (Employee Stock Purchase Plan [Member], USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Employee Stock Purchase Plan [Member]
Compensation expense for benefit plans	$ 1,500,000	$ 1,300,000	$ 1,100,000
Income tax benefit from compensation expense for benefit plans	$ 600,000	$ 500,000	$ 400,000
Issuance of common stock under employee benefit plans, net of forfeitures and shares withheld to cover taxes, shares	114,600	134,500	152,900
Average grant-date fair value of shares issued during the period in compensation and benefit plans other than stock options	$ 75.42	$ 53.93	$ 40.86