Stockholders' Equity - Summary of Outstanding Warrants (Detail) - $ / shares	6 Months Ended
	Jun. 27, 2015	Mar. 25, 2015	Feb. 14, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding			916,858
(1) Warrants Related to February 2012 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	419,451
Common Shares, Currently Exercisable	419,451
Common shares, price per share	$ 16.20
Common Shares, Expiration Date	Feb. 22, 2017
(2) Warrants Related to November 2012 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	8,333
Common Shares, Currently Exercisable	8,333
Common shares, price per share	$ 4.50
Common Shares, Expiration Date	Nov. 26, 2015
(3) Warrants Related to December 2012 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	15,625
Common Shares, Currently Exercisable	15,625
Common shares, price per share	$ 4.50
Common Shares, Expiration Date	Dec. 18, 2015
(4) Warrants Related to April 2013 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	256,913
Common Shares, Currently Exercisable	256,913
Common shares, price per share	$ 5.45
Common Shares, Expiration Date	Apr. 26, 2019
(5) Warrants Related to August 2013 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	117,670
Common Shares, Currently Exercisable	117,670
Common shares, price per share	$ 2.25
Common Shares, Expiration Date	Aug. 05, 2016
(6) Warrants Related to August 2013 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	6,117,383
Common Shares, Currently Exercisable	6,117,383
Common shares, price per share	$ 1.63
Common Shares, Expiration Date	Aug. 09, 2018
(7) Warrants Related to August 2013 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	1,389,802
Common Shares, Currently Exercisable	1,389,802
Common shares, price per share	$ 1.63		$ 2.00
Common Shares, Expiration Date	Aug. 09, 2015
(8) Warrants Related to February 2015 Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	45,843		45,843
Common Shares, Currently Exercisable	0
Common shares, price per share	$ 3.00		$ 3.003
Common Shares, Expiration Date	Feb. 13, 2020
(9) Warrants Related to March 2015 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	1,531,395	1,531,395
Common Shares, Currently Exercisable	1,531,395
Common shares, price per share	$ 1.63	$ 1.6325
Common Shares, Expiration Date	Sep. 25, 2020
(10) Warrants Related to March 2015 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	153,140	153,140
Common Shares, Currently Exercisable	0
Common shares, price per share	$ 2.04	$ 2.0406
Common Shares, Expiration Date	Mar. 20, 2020