Basis of Presentation and Significant Accounting Policies - New Accounting Pronouncements - Recently Adopted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Revised Statements of Operations and Comprehensive Loss
Product revenue, net	$ 2,139	$ 276
License revenue	934	24
Cost of sales - product	444	79
Loss from operations	133,245	87,101
Net loss	$ (136,725)	$ (90,980)
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)	$ (2.55)	$ (2.22)
Revised Statement of Financial Position
Accounts receivable	$ 6,061		$ 6,195
Other current assets	13,625		10,515
Accrued expenses	68,975		68,700
Deferred revenue, current	95		95
Deferred revenue, non-current	282		305
Accumulated deficit	(1,110,486)		(973,761)
Revised Statement of Cash Flow
Net loss	(136,725)	$ (90,980)
Adjustments to reconcile net loss to net cash used in operating activities:
Accounts receivable	134	2,561
Other assets	(3,462)	(656)
Accrued expenses	(1,847)	3,923
Deferred revenues	(22)	(15)
Cash and cash equivalents at beginning of period	785,877	230,146
Cash and cash equivalents at end of period	672,239	314,460
Accounting Standards Updates 2016-09
Revised Statements of Operations and Comprehensive Loss
Product revenue, net		276
License revenue		24
Cost of sales - product		79
Loss from operations		87,101
Net loss		$ (90,980)
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)		$ (2.22)
Revised Statement of Financial Position
Accounts receivable			6,195
Other current assets			10,515
Accrued expenses			68,700
Deferred revenue, current			95
Deferred revenue, non-current			305
Accumulated deficit			(973,761)
Revised Statement of Cash Flow
Net loss		$ (90,980)
Adjustments to reconcile net loss to net cash used in operating activities:
Accounts receivable		2,561
Other assets		(656)
Accrued expenses		3,923
Deferred revenues		(15)
Cash and cash equivalents at beginning of period		230,146
Cash and cash equivalents at end of period		314,460
Effect of change | Accounting Standards Updates 2016-09
Revised Statements of Operations and Comprehensive Loss
Product revenue, net		103
License revenue		(110)
Cost of sales - product		3
Loss from operations		10
Net loss		(10)
Revised Statement of Financial Position
Accounts receivable			852
Other current assets			1,596
Accrued expenses			429
Deferred revenue, current			(193)
Deferred revenue, non-current			305
Customer deposit			(15,000)
Accumulated deficit			16,907
Revised Statement of Cash Flow
Net loss		(10)
Adjustments to reconcile net loss to net cash used in operating activities:
Accounts receivable		2,938
Other assets		(374)
Accrued expenses		198
Deferred revenues		(2,752)
As originally reported under Topic 605 | Accounting Standards Updates 2016-09
Revised Statements of Operations and Comprehensive Loss
Product revenue, net		173
License revenue		134
Cost of sales - product		76
Loss from operations		87,091
Net loss		$ (90,970)
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)		$ (2.22)
Revised Statement of Financial Position
Accounts receivable			5,343
Other current assets			8,919
Accrued expenses			68,271
Deferred revenue, current			288
Customer deposit			15,000
Accumulated deficit			$ (990,668)
Revised Statement of Cash Flow
Net loss		$ (90,970)
Adjustments to reconcile net loss to net cash used in operating activities:
Accounts receivable		(377)
Other assets		(282)
Accrued expenses		3,725
Deferred revenues		2,737
Cash and cash equivalents at beginning of period		230,146
Cash and cash equivalents at end of period		$ 314,460
Collaborative Arrangement | Zai Lab (Shanghai) Co., Ltd.
Impact of Adoption
Previously recognized revenue	0
Impact of potential future payments on transaction price	$ 0