Activity for the Company's stock options (Details) (Stock Options [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning of period, shares	3,142,000	3,552,000	4,018,000
Outstanding, beginning of period, weighted average exercise price	$ 59.86	$ 54.35	$ 49.53
Granted, shares	1,234,000	276,000	813,000
Granted, weighted average exercise price	$ 136.75	$ 108.89	$ 69.00
Exercised, shares	(640,000)	(543,000)	(371,000)
Exercised, weighted average exercise price	$ 52.50	$ 51.22	$ 40.57
Canceled, shares	(47,000)	(143,000)	(908,000)
Canceled, weighted average exercise price	$ 104.57	$ 50.54	$ 51.74
Outstanding, end of period, shares	3,689,000	3,142,000	3,552,000
Outstanding, end of period, weighted average exercise price	$ 86.29	$ 59.86	$ 54.35
Weighted average remaining contractual life (in years)	7 years	7 years	8 years
Options exercisable, end of period, shares	1,317,000	1,128,000	469,000
Options exercisable, end of period, weighted average exercise price	$ 55.65	$ 52.07	$ 46.23
Weighted average fair value of options granted	$ 55.08	$ 41.52	$ 28.17