Teijin Agreement - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Aug. 31, 2016	Mar. 31, 2017	Dec. 31, 2016
Revenue Recognition Milestone Method [Line Items]
Upfront payment from collaboration partner		$ 40,000,000	$ 40,000,000
Teijin Limited [Member] | License and Supply Agreement [Member]
Revenue Recognition Milestone Method [Line Items]
Potential to receive development milestone	$ 35,000,000
Percentage of running royalty and transfer pricing receivable range, high	20.00%
Percentage of running royalty and transfer pricing receivable range, mid	30.00%
Agreement expiration terms		The Agreement continues until the earlier of (i) twelve years after the first commercial sale of a licensed product in Japan, or (ii) the expiration of certain Versartis patents, unless terminated earlier by mutual agreement of the parties. The initial term of the Agreement is subject to automatic extension for three three-year terms, unless otherwise mutually agreed. The Agreement may be earlier terminated by either party for the other party’s uncured material breach or insolvency. In addition, Teijin may terminate the Agreement without cause upon six months’ advance notice prior to the sale of a licensed product, and upon twelve months’ notice thereafter.
Agreement expiration period after commercialization		12 years
Agreement automatic extension term		3 years
Upfront payment from collaboration partner		$ 40,000,000
Teijin Limited [Member] | License and Supply Agreement [Member] | Upfront Payment Arrangement [Member]
Revenue Recognition Milestone Method [Line Items]
Payments received under license and supply agreement	$ 40,000,000
Maximum [Member] | License and Supply Agreement [Member]
Revenue Recognition Milestone Method [Line Items]
Costs associated with additional trials	5,000,000
Maximum [Member] | Teijin Limited [Member] | License and Supply Agreement [Member]
Revenue Recognition Milestone Method [Line Items]
Potential to receive regulatory milestone	55,000,000
Potential to receive sales milestone	$ 35,000,000