Share-Based Compensation and Benefit Plans (Summary of Stock Options) (Details) - Stock option [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-Based Compensation and Benefit Plans
Exercisable at the end of the year, average remaining contractual term	4 years 5 months 7 days	3 years 9 months 21 days	3 years 10 months 14 days
Employee stock option [Member]
Share-Based Compensation and Benefit Plans
Outstanding beginning balance, shares	2,364
Outstanding at the beginning of the year, weighted-average exercise price	$ 137.08
Granted, shares	293
Granted, weighted-average exercise price	$ 264.34
Exercised, shares	(763)
Exercised, weighted-average exercise price	$ 80.52
Forfeited, shares	(34)
Forfeited, weighted-average exercise price	$ 231.53
Outstanding ending balance, shares	1,860	2,364
Outstanding at the end of the year, weighted-average exercise price	$ 178.57	$ 137.08
Outstanding at the end of the year, average remaining contractual term	5 years 10 months 10 days
Outstanding at the end of the year, aggregate intrinsic value	$ 308,297
Vested or expected to vest at the end of the year, shares	1,819
Vested or expected to vest at the end of the year, weighted-average exercise price	$ 176.78
Vested or expected to vest at the end of the year, average remaining contractual term	5 years 9 months 19 days
Vested or expected to vest at the end of the year, aggregate intrinsic value	$ 304,818
Exercisable at the end of the year, shares	1,174
Exercisable at the end of the year, weighted-average exercise price	$ 133.24
Exercisable at the end of the year, average remaining contractual term	4 years 5 months 7 days
Exercisable at the end of the year, aggregate intrinsic value	$ 247,816