Additional Information Regarding Outstanding, Exercisable and Vested and Exercisable Stock Options (Detail) (USD $)	Dec. 31, 2011 Year	Dec. 31, 2010
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Range of Exercise Prices, Lower Limit	$ 0.30
Options Outstanding - Range of Exercise Prices, Upper Limit	$ 710.84
Options Outstanding - Number of Shares	9,807,252	11,525,422
Options Outstanding - Weighted-Average Remaining Life (in years)	5.7
Options Outstanding - Weighted-Average Exercise Price	$ 357.92	$ 330.24
Options Exercisable - Number of Shares	6,263,104
Options Exercisable - Weighted-Average Exercise Price	$ 313.68
Options Exercisable and Vested - Number of Shares	6,244,783
Options Exercisable and Vested - Weighted-Average Exercise Price	$ 314.38
Range 1
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Range of Exercise Prices, Lower Limit	$ 0.30
Options Outstanding - Range of Exercise Prices, Upper Limit	$ 94.80
Options Outstanding - Number of Shares	297,360
Options Outstanding - Weighted-Average Remaining Life (in years)	2.6
Options Outstanding - Weighted-Average Exercise Price	$ 28.06
Options Exercisable - Number of Shares	296,392
Options Exercisable - Weighted-Average Exercise Price	$ 27.85
Options Exercisable and Vested - Number of Shares	278,071
Options Exercisable and Vested - Weighted-Average Exercise Price	$ 24.73
Range 2
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Range of Exercise Prices, Lower Limit	$ 117.84
Options Outstanding - Range of Exercise Prices, Upper Limit	$ 198.41
Options Outstanding - Number of Shares	412,843
Options Outstanding - Weighted-Average Remaining Life (in years)	2.9
Options Outstanding - Weighted-Average Exercise Price	$ 179.12
Options Exercisable - Number of Shares	412,843
Options Exercisable - Weighted-Average Exercise Price	$ 179.12
Options Exercisable and Vested - Number of Shares	412,843
Options Exercisable and Vested - Weighted-Average Exercise Price	$ 179.12
Range 3
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Range of Exercise Prices, Lower Limit	$ 205.96
Options Outstanding - Range of Exercise Prices, Upper Limit	$ 298.86
Options Outstanding - Number of Shares	505,760
Options Outstanding - Weighted-Average Remaining Life (in years)	3.2
Options Outstanding - Weighted-Average Exercise Price	$ 275.21
Options Exercisable - Number of Shares	502,038
Options Exercisable - Weighted-Average Exercise Price	$ 275.12
Options Exercisable and Vested - Number of Shares	502,038
Options Exercisable and Vested - Weighted-Average Exercise Price	$ 275.12
Range 4
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Range of Exercise Prices, Lower Limit	$ 300.97
Options Outstanding - Range of Exercise Prices, Upper Limit	$ 399.00
Options Outstanding - Number of Shares	5,478,754
Options Outstanding - Weighted-Average Remaining Life (in years)	5.0
Options Outstanding - Weighted-Average Exercise Price	$ 309.68
Options Exercisable - Number of Shares	4,012,895
Options Exercisable - Weighted-Average Exercise Price	$ 309.71
Options Exercisable and Vested - Number of Shares	4,012,895
Options Exercisable and Vested - Weighted-Average Exercise Price	$ 309.71
Range 5
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Range of Exercise Prices, Lower Limit	$ 401.78
Options Outstanding - Range of Exercise Prices, Upper Limit	$ 499.07
Options Outstanding - Number of Shares	935,944
Options Outstanding - Weighted-Average Remaining Life (in years)	6.6
Options Outstanding - Weighted-Average Exercise Price	$ 439.16
Options Exercisable - Number of Shares	514,417
Options Exercisable - Weighted-Average Exercise Price	$ 437.28
Options Exercisable and Vested - Number of Shares	514,417
Options Exercisable and Vested - Weighted-Average Exercise Price	$ 437.28
Range 6
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Range of Exercise Prices, Lower Limit	$ 501.27
Options Outstanding - Range of Exercise Prices, Upper Limit	$ 595.35
Options Outstanding - Number of Shares	1,892,340
Options Outstanding - Weighted-Average Remaining Life (in years)	8.4
Options Outstanding - Weighted-Average Exercise Price	$ 532.44
Options Exercisable - Number of Shares	509,780
Options Exercisable - Weighted-Average Exercise Price	$ 524.69
Options Exercisable and Vested - Number of Shares	509,780
Options Exercisable and Vested - Weighted-Average Exercise Price	$ 524.69
Range 7
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Range of Exercise Prices, Lower Limit	$ 601.17
Options Outstanding - Range of Exercise Prices, Upper Limit	$ 699.35
Options Outstanding - Number of Shares	284,171
Options Outstanding - Weighted-Average Remaining Life (in years)	9.1
Options Outstanding - Weighted-Average Exercise Price	$ 610.18
Options Exercisable - Number of Shares	14,659
Options Exercisable - Weighted-Average Exercise Price	$ 612.09
Options Exercisable and Vested - Number of Shares	14,659
Options Exercisable and Vested - Weighted-Average Exercise Price	$ 612.09
Range 8
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Range of Exercise Prices, Lower Limit	$ 710.84
Options Outstanding - Range of Exercise Prices, Upper Limit	$ 710.84
Options Outstanding - Number of Shares	80
Options Outstanding - Weighted-Average Remaining Life (in years)	6.0
Options Outstanding - Weighted-Average Exercise Price	$ 710.84
Options Exercisable - Number of Shares	80
Options Exercisable - Weighted-Average Exercise Price	$ 710.84
Options Exercisable and Vested - Number of Shares	80
Options Exercisable and Vested - Weighted-Average Exercise Price	$ 710.84