Summary of Significant Accounting Policies - EPS and SBC (Details)				1 Months Ended						2 Months Ended		3 Months Ended		6 Months Ended		9 Months Ended	12 Months Ended
	Jun. 13, 2017 shares	Dec. 09, 2016 shares	Sep. 26, 2016 USD ($) shares	Jun. 30, 2017 USD ($) $ / shares shares	Feb. 28, 2017 $ / shares shares	Dec. 31, 2016 $ / shares shares	Sep. 30, 2016 shares	Aug. 31, 2016 $ / shares shares	Nov. 30, 2015 shares	Sep. 30, 2016 item	Dec. 31, 2015	Jun. 30, 2017 USD ($) item $ / shares shares	Jun. 30, 2016 USD ($) item $ / shares shares	Jun. 30, 2017 USD ($) employee item $ / shares shares	Jun. 30, 2016 USD ($) item $ / shares shares	Jun. 30, 2017 USD ($) item $ / shares shares	Dec. 31, 2016 $ / shares shares
Computation of Net Loss per Common Share
Options outstanding to purchase common stock and unvested restricted stock												15,588,000	11,919,000	15,588,000	11,919,000
Common stock equivalents under treasury stock method for options (in shares)												1,224,000	232,000	463,000	297,000
Shares issuable upon conversion of convertible notes (in shares) | item												23,878	23,878	23,878	23,878
Common stock equivalents under if-converted method for convertible notes (in shares)												23,878,000	2,886,000	23,878,000	1,443,000
Additional disclosure for options
Cash received for exercise of stock options | $														$ 32,000	$ 370,000
Stock compensation expense (reduction) | $												$ 3,100,000	$ 4,500,000	5,700,000	11,600,000
Estimated fair value of unvested employee awards, net of estimated forfeitures | $				$ 15,000,000								$ 15,000,000		$ 15,000,000		$ 15,000,000
Weighted average vesting period of unvested employee awards														2 years
Chief Executive Officer
Additional disclosure for options
Stock compensation cost due to modification | $															$ 3,100,000
Stock options
Weighted-average assumptions used to estimate the fair value of each stock option
Dividend (as a percent)												0.00%	0.00%	0.00%	0.00%
Volatility (as a percent)												68.17%	64.13%	67.10%	64.06%
Risk-free interest rate (as a percent)												1.90%	1.40%	2.01%	1.46%
Expected life												6 years	6 years 3 months 18 days	6 years	6 years 3 months 18 days
Weighted-average grant date fair value (in dollars per share) | $ / shares												$ 2.86	$ 3.44	$ 1.75	$ 4.10
Number of Stock Options
Outstanding at the beginning of the period (in shares)														13,679
Granted (in shares)														1,428
Exercised (in shares)														(10)
Forfeited/Canceled (in shares)														(1,916)
Outstanding at the end of the period (in shares)				13,181		13,679						13,181		13,181		13,181	13,679
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares														$ 10.70
Granted (in dollars per share) | $ / shares														2.84
Exercised (in dollars per share) | $ / shares														3.30
Forfeited/Canceled (in dollars per share) | $ / shares														10.47
Outstanding at the end of the period (in dollars per share) | $ / shares				$ 9.89		$ 10.70						$ 9.89		$ 9.89		$ 9.89	$ 10.70
Additional disclosure for options
Cash received for exercise of stock options | $															$ 32,000
Restricted stock
Stock-Based Compensation
Exercise period										5 years						5 years
Number of equal installments restrictions lapse | item										3						3
Number of Restricted Stock
Unvested at the beginning of the period (in shares)														199,000
Awarded (in shares)														2,253,000
Vested (in shares)														(25,000)
Forfeited (in shares)														(20,000)
Unvested at the end of the period (in shares)				2,407,000		199,000						2,407,000		2,407,000		2,407,000	199,000
Weighted-Average Exercise Price
Awarded (in dollars per share) | $ / shares								$ 3.15
Additional disclosure for options
Stock compensation expense (reduction) | $														$ 0
Restricted stock | Officers
Number of Restricted Stock
Awarded (in shares)				239,000	529,830			117,800
Weighted-Average Exercise Price
Awarded (in dollars per share) | $ / shares				$ 4.71	$ 2.47			$ 3.15
Compensation Policy for Non-Employee Directors
Number of Stock Options
Granted (in shares)				80,000
Additional disclosure for options
Stock compensation expense (reduction) | $												$ 47,000	$ 10,800	$ 85,000	$ 215,000
Compensation Policy for Non-Employee Directors | Stock options
Stock-Based Compensation
Vesting period											1 year			1 year			1 year
Number of Stock Options
Granted (in shares)						40,000			80,000
Compensation Policy for Non-Employee Directors | Deferred share units
Stock-Based Compensation
Vesting period		1 year
2016 Plan
Computation of Net Loss per Common Share
Common stock equivalents under treasury stock method for options (in shares)		14,250,000
Stock-Based Compensation
Number of employee share-based compensation plans | employee														1
Additional shares authorized for issuance (in shares)	1,000,000
Common stock authorized for issuance (in shares)		5,500,000
2016 Plan | Stock options
Weighted-average assumptions used to estimate the fair value of each stock option
Number of group of awards for which expected term is calculated for and applied | item														1
2016 Plan | Stock options | Maximum
Stock-Based Compensation
Vesting period														4 years
Exercise period														10 years
Workforce reduction
Stock-Based Compensation
Vesting period							3 years
Number of Stock Options
Granted (in shares)							750,000
Workforce reduction | Stock options
Number of Stock Options
Forfeited/Canceled (in shares)			(762,000)
Additional disclosure for options
Stock compensation expense (reduction) | $			$ 837,000