Share-Based Compensation and Benefit Plans (Summary of Restricted Stock) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Employee Stock [Member]
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 granted during the period, shares	16
Restricted stock granted during period, weighted-average grant date fair value	$ 100.82
Restricted stock vested during the period, shares	(22)	[1]
Restricted stock vested during the period, weighted-average grant date fair value	$ 73.67	[1]
Restricted stock forfeited during the period, shares	(1)
Restricted stock forfeited during the period, weighted-average grant date fair value	$ 83.06
Non-vested restricted stock at December 31, 2013 shares	20
Non-vested restricted stock at December 31, 2013 weighted-average grant date fair value	$ 92.02
Restricted Stock [Member]
Restricted stock granted during period, weighted-average grant date fair value	$ 102.63		$ 90.10	$ 56.18
Director [Member] | Restricted Stock [Member]
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
Restricted stock granted during the period, shares	5
Restricted stock granted during period, weighted-average grant date fair value	$ 109.45
Restricted stock vested during the period, shares	(4)
Restricted stock vested during the period, weighted-average grant date fair value	$ 75.39
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, 2013 shares	11
Non-vested restricted stock at December 31, 2013 weighted-average grant date fair value	$ 94.18

[1] Includes 9 thousand shares withheld to cover employees' taxes upon vesting.