Lease Agreements and Power Purchase Agreements - Minimum Future Rental Receipts on Operating Leases (Details) $ in Thousands	May 31, 2016 USD ($)
Operating Leased Assets [Line Items]
Minimum future rentals on residential operating leases, 2016 (remaining six months)	$ 4,524
Minimum future rentals on residential operating leases, 2017	8,938
Minimum future rentals on residential operating leases, 2018	8,900
Minimum future rentals on residential operating leases, 2019	8,660
Minimum future rentals on residential operating leases, 2020	3,769
Minimum future rentals on residential operating leases, Thereafter	46,404
Minimum future rentals on residential operating leases, Total	81,195
Minimum future rentals on residential operating leases placed in service
Operating Leased Assets [Line Items]
Minimum future rentals on residential operating leases, 2016 (remaining six months)	1,846
Minimum future rentals on residential operating leases, 2017	3,707
Minimum future rentals on residential operating leases, 2018	3,727
Minimum future rentals on residential operating leases, 2019	3,748
Minimum future rentals on residential operating leases, 2020	3,769
Minimum future rentals on residential operating leases, Thereafter	46,404
Minimum future rentals on residential operating leases, Total	63,201
Maryland Solar Lease
Operating Leased Assets [Line Items]
Minimum future rentals on residential operating leases, 2016 (remaining six months)	2,678
Minimum future rentals on residential operating leases, 2017	5,231
Minimum future rentals on residential operating leases, 2018	5,173
Minimum future rentals on residential operating leases, 2019	4,912
Minimum future rentals on residential operating leases, 2020	0
Minimum future rentals on residential operating leases, Thereafter	0
Minimum future rentals on residential operating leases, Total	$ 17,994