Nature of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Apr. 30, 2019	Mar. 31, 2019	Nov. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018	Apr. 12, 2017
Liquidity
Net loss attributable to common shareholders					$ 21,242	$ 15,578	$ 73,767	$ 61,307	$ 78,200	$ 130,200	$ 57,600
Accumulated deficit	$ 1,334,057				1,334,057		1,334,057		1,260,290
Net cash used in operating activities							51,801	41,642
Net loss attributable to the Company					(21,229)	$ (15,565)	(73,728)	(61,268)
Net outflows from fluctuations in working capital and other assets and liabilities							13,400
Non-cash charges							35,400
Cash and cash equivalents	43,275				43,275		43,275		38,602
Net working capital	70,500				70,500		70,500		9,200
Net cash used in investing activities							(8,971)	(17,528)
Net cash provided by financing activities							149,055	53,216
Sale of common stock			$ 23,500				38,098	4,912
Proceeds from borrowing of long-term debt							99,496
Increase in cash flows from new finance obligations							57,249
Proceeds from issuance of debt							39,052	95,856
Principal amount	100,000				100,000		100,000
Purchase of capped call and common stock forward								43,500
Remaining lease payments	168,900				168,900		168,900
Security on lease	162,000				162,000		162,000
Letter of credit	79,000				79,000		79,000
Cash Collateral for Borrowed Securities	6,400				6,400		6,400
Repayments of finance obligations							59,461	$ 25,138
Payments for redemption of preferred stock							4,040
Number of common stock sold			10,000,000
Share price (in dollars per share)			$ 2.35
Warrants issued in December 2016
Liquidity
Shares of common stock that can be purchased from warrants issued (in shares)													5,250,750
Per share price of shares of common stock													$ 2.69
Additional Master Lease Agreements
Liquidity
Remaining lease payments	57,300				57,300		57,300
Wells Fargo
Liquidity
Remaining lease payments	97,600				97,600		97,600
Letter of credit	37,300				37,300		37,300		$ 37,300
Loan and security agreement | Generate Lending, LLC
Liquidity
Termination of certain equipment leases							50,300
Repayments of finance obligations			$ 17,600				17,600
Loan and security agreement | Generate Lending, LLC | Secured term loan facility
Liquidity
Proceeds from borrowing of long-term debt		$ 15,000	85,000
Termination of certain equipment leases			$ 50,300
Convertible Senior Notes
Liquidity
Proceeds from issuance of debt							39,100
Principal amount	$ 40,000				$ 40,000		$ 40,000
Interest rate (as a percent)	7.50%				7.50%		7.50%
$40M Convertible Senior Note
Liquidity
Proceeds from issuance of debt	$ 39,100
Principal amount	$ 40,000				$ 40,000		$ 40,000
Interest rate (as a percent)	7.50%				7.50%		7.50%
Obligation, net of interest accretion	$ 48,000				$ 48,000		$ 48,000
$100M Convertible Senior Notes
Liquidity
Proceeds from issuance of debt							52,356
Principal amount	$ 100,000				$ 100,000		$ 100,000					$ 100,000
Interest rate (as a percent)	5.50%				5.50%		5.50%					5.50%
Purchase of capped call and common stock forward							$ 43,500
Share price (in dollars per share)	$ 2.63				$ 2.63		$ 2.63
Series E Preferred Stock
Liquidity
Number of redeemed shares					4,038
Amount of redeemed shares					$ 4,000
Series E Redeemable Convertible Preferred Stock
Liquidity
Shares issued (in shares)				35,000
Redeemable stock issued, stated value (in dollars per share)	$ 0.01			$ 0.01	$ 0.01		$ 0.01		$ 0.01
Aggregate proceeds from issuance of preferred stock				$ 30,900
At Market Issuance Sales Agreement
Liquidity
Sale of common stock							$ 14,800
Number of common stock sold							6,300,000