Summary of Significant Accounting Policies - Additional Information (Details)		3 Months Ended
	Nov. 18, 2016 shares	Mar. 31, 2017 USD ($) shares	Mar. 31, 2016 USD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Disclosure Summary Of Significant Accounting Policies Additional Information Detail [Line Items]
Accumulated deficit		$ (102,048,429)		$ (96,223,442)
Cash and cash equivalents		5,341,433	$ 17,514,213	11,437,118	$ 22,604,481
Certificates of deposit		$ 466,111		$ 3,462,617
Shares authorized but unissued common stock (in shares) | shares		19,500,060
Tax benefit attributed to the stock-based compensation expense		$ 0
Unrecognized tax benefits		0
Liability, interest, or penalties related to unrecognized tax benefits		$ 0
Reverse split ratio	0.025
Common stock authorized (in shares) | shares	25,000,000	25,000,000		25,000,000
Shares excluded from the computation of diluted net loss per share (in shares) | shares		1,727,017	908,056
Intellectual Property
Disclosure Summary Of Significant Accounting Policies Additional Information Detail [Line Items]
Fair value of intellectual property						$ 11,000,000
Computer Equipment
Disclosure Summary Of Significant Accounting Policies Additional Information Detail [Line Items]
Estimated useful lives of property and equipment		3 years
Minimum
Disclosure Summary Of Significant Accounting Policies Additional Information Detail [Line Items]
Estimated useful lives of property and equipment		3 years
Maximum
Disclosure Summary Of Significant Accounting Policies Additional Information Detail [Line Items]
Estimated useful lives of property and equipment		5 years