Share-Based Compensation - Share-Based Payment Award Activity (Detail) - Jun. 30, 2015 - USD ($)	Total
Options
Outstanding, beginning of period	1,394,888
Granted	122,120
Exercised	(286,282)
Forfeited	(17,383)
Expired	(1,520)
Outstanding, end of period	1,211,823
Vested and expected to vest, end of period	1,168,962
Exercisable, end of period	678,385
Weighted Average Exercise Price
Outstanding, beginning of period	$ 66.03
Granted	129.30
Exercised	51.34
Forfeited	86.09
Expired	48.76
Outstanding, end of period	75.61
Vested and expected to vest, end of period	74.62
Exercisable, end of period	$ 59.89
Weighted Average Remaining Contractual Life in Years
Outstanding, end of period	4 years 2 months 21 days
Vested and expected to vest, end of period	4 years 1 month 30 days
Exercisable, end of period	3 years 2 months 23 days
Aggregate Intrinsic Value of In-The- Money Options
Outstanding, end of period	$ 82,851,473
Vested and expected to vest, end of period	81,084,324
Exercisable, end of period	$ 57,044,065