- Stock Option Activity and Weighted Average Exercise Price (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Outstanding Shares
Forfeited	0
Stock Option Plans
Outstanding Shares
Beginning Balance	4,105,539	4,206,512	4,466,080
Granted	1,326,430	743,062	705,564
Exercised	(348,206)	(706,750)	(866,917)
Forfeited	(366,702)	(137,285)	(98,215)
Ending Balance	4,717,061	4,105,539	4,206,512
Vested or expected to vest at end of period	4,717,061
Options exercisable at end of period	2,199,084
Weighted-Average Exercise Price
Beginning Balance	$ 84.61	$ 66.38	$ 49.29
Granted	78.72	150.81	130.10
Exercised	40.51	40.21	30.33
Forfeited	108.90	112.95	65.14
Ending Balance	84.32	$ 84.61	$ 66.38
Vested or expected to vest at end of period	84.32
Options exercisable at end of period	$ 62.60
Omnibus Incentive Plan
Outstanding Shares
Beginning Balance	18,950	63,233	162,431
Exercised	(18,950)	(44,283)	(96,398)
Forfeited		0	(2,800)
Ending Balance	0	18,950	63,233
Vested or expected to vest at end of period	0
Options exercisable at end of period	0
Weighted-Average Exercise Price
Beginning Balance	$ 23.37	$ 23.76	$ 23.74
Exercised	23.37	23.92	23.77
Forfeited	0.00	0.00	22.43
Ending Balance	0.00	$ 23.37	$ 23.76
Vested or expected to vest at end of period	0.00
Options exercisable at end of period	$ 0.00