Stockholders' Equity - Issuance of Common Stock and Warrants (Details) $ / shares in Units, shares in Millions		1 Months Ended	3 Months Ended
	Mar. 28, 2017 USD ($) $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares	Apr. 01, 2018 USD ($) $ / shares	Apr. 02, 2017 USD ($)	Dec. 31, 2017 $ / shares	Jun. 30, 2017 $ / shares shares	Mar. 16, 2017 USD ($) offering
Class of Stock [Line Items]
Shelf registration, number of offerings | offering							1
Shelf registration, maximum offering | $							$ 40,000,000.0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001		$ 0.001
Underwritten public offering price (in dollars per share)	$ 1.50	$ 1.50	$ 1.52
Net proceeds from issuance of common stock | $	$ 15,200,000	$ 15,200,000	$ 0	$ 17,069,000
June 2012 financing
Class of Stock [Line Items]
Warrants outstanding (in shares) | shares						2.3
Strike price of warrants (in dollars per share)						$ 2.98
Common stock
Class of Stock [Line Items]
Aggregate shares of common stock issued | shares	11.3	11.3