Earnings Per Share (Computation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator (basic and diluted):
Net income		$ 278,493	$ 266,268	$ 791,661	$ 712,640
Denominator:
Weighted-average common shares outstanding - basic		94,891	99,270	95,994	100,468
Effect of stock options	[1]	1,229	1,500	1,315	1,573
Weighted-average common shares outstanding - assuming dilution		96,120	100,770	97,309	102,041
Earnings per share - basic		$ 2.93	$ 2.68	$ 8.25	$ 7.09
Earnings per share - assuming dilution		$ 2.90	$ 2.64	$ 8.14	$ 6.98
Antidilutive stock options	[1]	271	176	319	256
Weighted-average exercise price	[1]	$ 267.66	$ 218.21	$ 264.88	$ 210.49

[1] See Note 6 for further information concerning the terms of the Company’s share-based compensation plans.