Stock Options (Detail) - $ / shares	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Shares
Beginning balance, shares	2,591,565
Granted, shares	1,402,786
Vested/Issued	(977,257)
Forfeited	(214,110)
Ending balance, shares	2,802,984
Weighted Average Grant-Date Fair Value
Beginning balance, Weighted Average Grant-Date Fair Value	$ 81.33
Weighted-average grant date fair value of options granted	89.17	$ 86.83
Vested/Issued	61.22
Forfeited	110.20
Ending balance, Weighted Average Grant-Date Fair Value	$ 90.95