Options Outstanding and Exercisable - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Information regarding options outstanding and exercisable
Options Outstanding, Options	5,734,365
Options Outstanding, Weighted Average Remaining Contractual Life in Years	5 years 2 months 9 days
Options Outstanding, Weighted Average Exercise Price	$ 48.04
Options Exercisable, Options	4,436,990
Options Exercisable, Weighted Average Exercise Price	$ 45.11
Options, Vested and expected to vest	5,696,241
Options, Weighted Average Remaining Contractual Life in Years	5 years 25 days
Options, Weighted Average Exercise Price	$ 47.96
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	18.70
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 81.01
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value	$ 191.6
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 161.9
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	4 years 7 months 5 days
Market value of common shares	$ 81.59
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number		5,011,784	6,046,489
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price		$ 42.18	$ 38.76
Exercise Price Range One [Member]
Information regarding options outstanding and exercisable
Options Outstanding, Options	865,289
Options Outstanding, Weighted Average Remaining Contractual Life in Years	3 years 1 month 7 days
Options Outstanding, Weighted Average Exercise Price	$ 23.07
Options Exercisable, Options	865,289
Options Exercisable, Weighted Average Exercise Price	$ 23.07
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	18.70
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 24.93
Exercise Price Range Two [Member]
Information regarding options outstanding and exercisable
Options Outstanding, Options	634,733
Options Outstanding, Weighted Average Remaining Contractual Life in Years	4 years 1 month 7 days
Options Outstanding, Weighted Average Exercise Price	$ 32.97
Options Exercisable, Options	634,733
Options Exercisable, Weighted Average Exercise Price	$ 32.97
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	24.94
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 37.39
Exercise Price Range Three [Member]
Information regarding options outstanding and exercisable
Options Outstanding, Options	446,345
Options Outstanding, Weighted Average Remaining Contractual Life in Years	1 year 2 months 3 days
Options Outstanding, Weighted Average Exercise Price	$ 40.53
Options Exercisable, Options	446,345
Options Exercisable, Weighted Average Exercise Price	$ 40.53
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	37.40
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 43.62
Exercise Price Range Four [Member]
Information regarding options outstanding and exercisable
Options Outstanding, Options	2,056
Options Outstanding, Weighted Average Remaining Contractual Life in Years	4 years 10 months
Options Outstanding, Weighted Average Exercise Price	$ 48.63
Options Exercisable, Options	2,056
Options Exercisable, Weighted Average Exercise Price	$ 48.63
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	43.63
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 49.86
Exercise Price Range Five [Member]
Information regarding options outstanding and exercisable
Options Outstanding, Options	1,969,539
Options Outstanding, Weighted Average Remaining Contractual Life in Years	5 years 7 months
Options Outstanding, Weighted Average Exercise Price	$ 53.96
Options Exercisable, Options	1,278,111
Options Exercisable, Weighted Average Exercise Price	$ 54.06
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	49.87
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 56.09
Exercise Price Range Six [Member]
Information regarding options outstanding and exercisable
Options Outstanding, Options	1,648,650
Options Outstanding, Weighted Average Remaining Contractual Life in Years	6 years 11 months 2 days
Options Outstanding, Weighted Average Exercise Price	$ 58.65
Options Exercisable, Options	1,209,674
Options Exercisable, Weighted Average Exercise Price	$ 59.44
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	56.10
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 62.32
Exercise Price Range Seven [Member]
Information regarding options outstanding and exercisable
Options Outstanding, Options	2,353
Options Outstanding, Weighted Average Remaining Contractual Life in Years	9 years 5 months 26 days
Options Outstanding, Weighted Average Exercise Price	$ 71.35
Options Exercisable, Options	0
Options Exercisable, Weighted Average Exercise Price	$ 0.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	68.56
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 74.78
Exercise Price Range Eight [Member]
Information regarding options outstanding and exercisable
Options Outstanding, Options	165,400
Options Outstanding, Weighted Average Remaining Contractual Life in Years	9 years 1 month 8 days
Options Outstanding, Weighted Average Exercise Price	$ 80.27
Options Exercisable, Options	782
Options Exercisable, Weighted Average Exercise Price	$ 80.27
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	74.79
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 81.01