Nature of Operations (Details) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 01, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) agreement	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Liquidity
Net loss attributable to common shareholders		$ 13,420	$ 10,238	$ 38,354	$ 30,568	$ 55,800	$ 88,600	$ 62,800
Accumulated deficit		1,032,230		1,032,230		993,876
Net cash used in operating activities				29,669	37,296
Net loss attributable to the Company		(13,394)	(10,213)	(38,276)	(30,490)
Noncash gains				4,800
Net inflows of noncash operating assets and liabilities				3,800
Cash and cash equivalents		42,486	$ 85,009	42,486	$ 85,009	63,961	$ 146,205
Net working capital		50,400		50,400		88,500
Cash added to the restricted accounts		0		$ 0		$ 14,200
Number of power purchase agreements | agreement				7
Remaining lease payment		54,395		$ 54,395
Purchases of property, plant, and equipement and cash outflows associated with construction of leased assets				45,100
Subsequent event
Liquidity
Cash added to the restricted accounts	$ 12,000
Power purchase agreements
Liquidity
Remaining lease payment		$ 22,300		22,300
Master Lease
Liquidity
Minimum level of unrestricted cash				$ 40,000
Number of years that the underlying assets not be deployed				5 years
Residual exposure				$ 12,000
Secured term loan facility
Liquidity
Prior to net income milestones met, required minimum cash and cash equivalents percent of outstanding principal amount				75.00%
Accounts payable days outstanding threshold				150 days