Fair Value of Financial Assets and Liabilities - Derivative Instruments (Narrative) (Details) - USD ($)		3 Months Ended
	Apr. 08, 2016	Jun. 30, 2016	Dec. 31, 2016	Jun. 20, 2016	Dec. 31, 2015	Aug. 03, 2015	Aug. 02, 2015
Derivatives And Fair Value [Line Items]
Fair value transfers out of Level 1			$ 0		$ 0
Fair value transfers out of Level 2			$ 0		$ 0
Remaining shares authorized for issuance			670,000,000		670,000,000	670,000,000	445,000,000
Dilutive Financing Derivative Liability [Member]
Derivatives And Fair Value [Line Items]
Derivative liability			$ 126,000
Common Stock Issuance Agreement [Member]
Derivatives And Fair Value [Line Items]
Shares issued per agreement	853,465
Remaining shares authorized for issuance			286,846	1,037,053
Common Stock Issuance Agreement [Member] | Dilutive Financing Derivative Liability [Member]
Derivatives And Fair Value [Line Items]
Derivative liability	$ 2,300,000
Series B redeemable convertible preferred stock [Member]
Derivatives And Fair Value [Line Items]
Common stock closing price					$ 3.98
Gain on derivative liability		$ 91,000