Summary of Stock Awards Granted (Detail) - $ / shares	3 Months Ended			6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016	Jun. 30, 2017		Jun. 30, 2016
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Stock options	3,579,467	[1]	7,600	4,456,959	[1]	1,213,376
Weighted Average Grant Date Fair Value, Stock options	$ 13.64		$ 15.61	$ 14.16		$ 11.94
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Restricted stock units and awards	20,000			181,029	[2]
Weighted Average Grant Date Fair Value, Restricted stock units and awards	$ 36.26			$ 33.03
Restricted Stock Awards (RSAs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Restricted stock units and awards	335,000	[3]		341,500	[3]	25,775
Weighted Average Grant Date Fair Value, Restricted stock units and awards	$ 34.65			$ 34.58		$ 13.71

[1] The Company granted its new CEO 3,300,000 options with service and market conditions. These options have a five-year cliff vesting schedule. The fair value of $13.48 for these options was determined by a lattice model with Monte Carlo simulations. The remaining 279,467 service-based options which have a weighted average grant date fair value of $15.49 have a four-year vesting schedule with 25% vest on the first anniversary and 1/48 monthly thereafter.

[2] The Company granted certain executives 156,029 restricted stock units (“RSUs”) with certain sales target and regulatory milestones. As of June 30, 2017, one performance condition of these RSUs was achieved. As a result, 50% of these RSUs became immediately vested and, accordingly, the Company recorded $2.5 million of stock-based compensation expenses. As of June 30, 2017, the remaining two performance conditions have been deemed as not probable of being achieved. If and when deemed probable that such performance milestones may be achieved within the required time frame, the Company may recognize up to $2.6 million of stock-based compensation related to these grants. The remaining RSUs are service-based awards granted to the members of the board of directors.

[3] The Company granted its new CEO 335,000 restricted stock awards (“RSAs”) with a fair value of $34.65. These RSAs have a four-year vesting schedule with 25% vest on the first anniversary and 1/48 vest monthly thereafter.