Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Options outstanding, shares
Beginning Balance	1,323	1,201	600
Granted	45	380	745
Exercised	(112)	(91)	(9)
Forfeited/Expired	(370)	(167)	(135)
Ending Balance	886	1,323	1,201
Exercisable as of December 31, 2016	345
Expected to vest as of December 31, 2016	541
Total	886
Weighted Average Exercise Price Per Share
Beginning Balance	$ 129.04	$ 111.77	$ 92.84
Granted	189.62	178.93	125.46
Exercised	97.82	105.25	92.84
Forfeited/Expired	110.28	131.31	104.48
Ending Balance	143.89	$ 129.04	$ 111.77
Exercisable as of December 31, 2016	135.25
Expected to vest as of December 31, 2016	149.39
Total	$ 143.89
Aggregate Intrinsic Value
Exercised	$ 8,102	$ 6,367	$ 653
Exercisable as of December 31, 2016	21,520
Expected to vest as of December 31, 2016	26,303
Total	$ 47,823
Weighted Average Remaining Contractual Term (Years)
Exercisable as of December 31, 2016	7 years 7 months 6 days
Expected to vest as of December 31, 2016	7 years 10 months 24 days
Total	7 years 8 months 12 days