Activity with Respect to Options Granted (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Shares
Beginning balance, shares	5,542,285
Granted, shares	249,750
Forfeited, shares	(89,392)
Exercised, shares	(26,250)
Expired, shares	(1,000)
Ending balance, shares	5,675,393	5,542,285
Nonvested, shares	3,433,496	3,572,202
Exercisable, shares	2,241,897
Weighted Average Exercise Price
Beginning Balance, Weighted Average Exercise Price	$ 105.59
Granted, Weighted Average Exercise Price	60.82
Forfeited, Weighted Average Exercise Price	121.08
Exercised, Weighted Average Exercise Price	8.46
Expired, Weighted Average Exercise Price	106.41
Ending Balance, Weighted Average Exercise Price	103.83	$ 105.59
Nonvested, Weighted Average Exercise Price	118.33
Exercisable, Weighted Average Exercise Price	$ 81.62
Weighted Average Remaining Contractual Term (years)
Weighted Average Remaining Contractual Term (years)	8 years 4 months 24 days	8 years 7 months 6 days
Nonvested, Weighted Average Remaining Contractual Term (years)	9 years 2 months 12 days
Exercisable, Weighted Average Remaining Contractual Term (years)	7 years 2 months 12 days
Aggregate Intrinsic Value
Beginning balance, Aggregate Intrinsic Value	$ 87,632
Exercised, Aggregate Intrinsic Value	920
Ending balance, Aggregate Intrinsic Value	17,190	$ 87,632
Exercisable, Aggregate Intrinsic Value	$ 17,190