CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows From Operating Activities:
Net loss	$ (224,338)	$ (198,607)	$ (117,500)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	165	233	163
Amortization of deferred debt costs and debt discount	1,342	6,921	4,566
Accretion of back-end facility fee	106	0	0
Loss on disposal of property and equipment	46	0	0
Stock-based compensation expense	22,715	12,575	9,724
Interest expense — Payment-in-kind (PIK)	3,212	0	0
Value of common stock issued for patent license	0	0	67
Accretion of discount/premium on available for sale securities	0	0	(109)
Change in fair value of derivative instruments—warrants	(4,340)	(106)	394
Common stock issued for interest on Notes		2,445	0
Debt conversion expense	1,209	40,158	0
Changes in operating assets and liabilities:
Accounts receivable	(6,491)	0	0
Inventories	(11,574)	(5,640)	0
Security deposits	31	0	(180)
Accounts payable and accrued expenses	8,669	11,546	1,867
Prepaid expenses and other current assets	(3,580)	2,416	531
Accrued interest expense on senior convertible notes	(61)	(1,694)	(512)
Total Adjustments	11,449	68,854	16,511
Net Cash used in Operating Activities	(212,889)	(129,753)	(100,989)
Cash Flows From Investing Activities:
Net sales (purchases) of available-for-sale securities	0	50,097	(200)
Additions to property and equipment	(210)	(297)	(50)
Net Cash (used in) provided by Investing Activities	(210)	49,800	(250)
Cash Flows From Financing Activities:
Proceeds of sale of common stock, net of issuance costs	173,802	89,845	14,268
Proceeds from borrowings, net of issuance costs	95,140	0	0
Fees and expenses — note conversions	0	(711)	0
Payment for deferred financing costs	(1,591)	0	0
Proceeds from exercise of warrants	0	11,331	1,012
Proceeds from exercise of stock options	347	222	1,142
Net Cash provided by Financing Activities	267,698	100,687	16,422
Net increase (decrease) in cash and cash equivalents	54,599	20,734	(84,817)
Cash and cash equivalents at beginning of period	82,387	61,653	146,470
Cash and cash equivalents at end of period	136,986	82,387	61,653
Supplementary disclosure of cash flow information:
Cash paid for interest on senior convertible notes	1,396	5,939	13,379
Cash paid for taxes	20	45	258
Supplementary disclosure of non-cash investing and financing activities:
Conversion of senior convertible notes to Synergy Common Stock	4,912	137,941	40,989
Amount added to principal of term loan for Payment-in-kind (PIK) interest	3,212	0	0
Non-cash tenant improvement allowance	587	0	0
Fair value of warrants classified to derivative liability	$ 21,706	$ 0	$ 0