Share-Based Compensation Stock Option Information Related to Equity Incentive Plan (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Options
Outstanding, beginning of period (in shares) | shares	1,137,228.000
Granted (in shares) | shares	177,203
Exercised (in shares) | shares	(271,528)
Forfeited (in shares) | shares	(32,156)
Expired (in shares) | shares	(190)
Outstanding, end of period (in shares) | shares	1,010,557
Vested and expected to vest (in shares) | shares	985,983
Exercisable (in shares) | shares	580,165
Weighted average exercise price
Outstanding, beginning of period (usd per share) | $ / shares	$ 77.12
Granted (usd per share) | $ / shares	105.11
Exercised (usd per share) | $ / shares	54.78
Forfeited (usd per share) | $ / shares	102.51
Expired (usd per share) | $ / shares	19.48
Outstanding, end of period (usd per share) | $ / shares	87.24
Vested and expected to vest (usd per share) | $ / shares	86.69
Exercisable (usd per share) | $ / shares	$ 73.67
Weighted Average Remaining Contractual Life in Years
Outstanding (in years)	3 years 9 months 4 days
Vested and expected to vest (in years)	3 years 8 months 16 days
Exercisable (in years)	2 years 8 months 9 days
Aggregate Intrinsic Value of In-The-Money Options
Outstanding | $	$ 85,315,707
Vested and expected to vest | $	83,778,687
Exercisable | $	$ 56,848,539