Share-Based Employee Compensation Plans and Other Compensation and Benefit Plans (Summary of Restricted Stock) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Employee Stock [Member]
Non-vested restricted stock at December 31, 2011, shares	40
Non-vested restricted stock at December 31, 2011, weighted-average grant date fair value	$ 50.72
Restricted stock granted during the period, shares	18
Restricted stock granted during period, weighted-average grant date fair value	$ 86.90
Restricted stock vested during the period, shares	(30)	[1]
Restricted stock vested during the period, weighted-average grant date fair value	$ 55.11
Restricted stock forfeited during the period, shares	(1)
Restricted stock forfeited during the period, weighted-average grant date fair value	$ 61.08
Non-vested restricted stock at December 31, 2012, shares	27
Non-vested restricted stock at December 31, 2012, weighted-average grant date fair value	$ 70.64
Restricted Stock [Member]
Restricted stock granted during period, weighted-average grant date fair value	$ 90.10		$ 56.18	$ 39.57
Director [Member] | Restricted Stock [Member]
Non-vested restricted stock at December 31, 2011, shares	8
Non-vested restricted stock at December 31, 2011, weighted-average grant date fair value	$ 59.65
Restricted stock granted during the period, shares	5
Restricted stock granted during period, weighted-average grant date fair value	$ 102.39
Restricted stock vested during the period, shares	(3)
Restricted stock vested during the period, weighted-average grant date fair value	$ 59.65
Restricted stock forfeited during the period, shares	0
Restricted stock forfeited during the period, weighted-average grant date fair value	$ 0.00
Non-vested restricted stock at December 31, 2012, shares	10
Non-vested restricted stock at December 31, 2012, weighted-average grant date fair value	$ 79.58

[1] Includes 13 thousand shares withheld to cover employees' taxes upon vesting.