Indebtedness - Additional Information (Details) - USD ($)	1 Months Ended				12 Months Ended
	Jul. 31, 2015	Apr. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Line Of Credit Facility [Line Items]
Repayments of debt					$ 357,878,000	$ 120,054,000	$ 612,000
Loss on early extinguishment of debt					431,000	4,350,000
Loan outstanding balance			$ 239,251,000		538,318,000	239,251,000
Solar energy systems, gross			1,570,695,000		2,091,585,000	1,570,695,000
Repayment of lease obligations					$ 4,854,000	1,181,000
Basis point
Line Of Credit Facility [Line Items]
Annual Contractual Interest Rate					3.25%
Subordinated Term Loan
Line Of Credit Facility [Line Items]
Repayments of debt			94,400,000
Bank Line of Credit | Credit Facility Agreements with Syndicate of Banks
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			50,000,000			50,000,000
Bank Line of Credit | Credit Facility Agreements with Syndicate of Banks | Letter of Credit Sub-Facility
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			1,000,000			1,000,000
Bank Line of Credit | Syndicated Working Capital Facility
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 205,000,000
Minimum unencumbered liquid assets to be maintained					$ 25,000,000
Bank Line of Credit | Syndicated Working Capital Facility | Minimum
Line Of Credit Facility [Line Items]
Interest coverage ratio					200.00%
Non Bank Term Loans
Line Of Credit Facility [Line Items]
Aggregate amount of debt				$ 119,500,000			119,500,000
Repayments of debt		3,500,000
Loss on early extinguishment of debt		$ 400,000
Syndicated Term Loans | Credit Facility Agreements with Syndicate of Banks
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			195,400,000			195,400,000
Debt maturity date					Dec. 31, 2021
Syndicated Term Loans | Credit Facility Agreements with Syndicate of Banks | Senior Term Loan
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			$ 158,500,000			158,500,000
Syndicated Term Loans | Credit Facility Agreements with Syndicate of Banks | Senior Term Loan | Basis point
Line Of Credit Facility [Line Items]
Debt instrument, variable rate periodic increase			0.25%
Annual Contractual Interest Rate			2.75%
Syndicated Term Loans | Credit Facility Agreements with Syndicate of Banks | Subordinated Term Loan
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			$ 24,000,000			24,000,000
Syndicated Term Loans | Credit Facility Agreements with Syndicate of Banks | Subordinated Term Loan | Minimum
Line Of Credit Facility [Line Items]
Debt prepayment penalty percentage			0.00%
Syndicated Term Loans | Credit Facility Agreements with Syndicate of Banks | Subordinated Term Loan | Minimum | Basis point
Line Of Credit Facility [Line Items]
Annual Contractual Interest Rate			1.00%
Syndicated Term Loans | Credit Facility Agreements with Syndicate of Banks | Subordinated Term Loan | Maximum
Line Of Credit Facility [Line Items]
Debt prepayment penalty percentage			2.00%
Syndicated Term Loans | Credit Facility Agreements with Syndicate of Banks | Subordinated Term Loan | Maximum | Basis point
Line Of Credit Facility [Line Items]
Annual Contractual Interest Rate			5.00%
Syndicated Term Loans | Credit Facility Agreements with Syndicate of Banks | Working Capital Revolver Commitment
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			$ 5,000,000			5,000,000
Syndicated Term Loans | Credit Facility Agreements with Syndicate of Banks | Senior Secured Revolving Letter Of Credit Facility
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			7,900,000			7,900,000
Bank Term Loans
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity				38,000,000			$ 38,000,000
Notes Payable
Line Of Credit Facility [Line Items]
Proceeds from issuance of senior secured notes				$ 27,200,000
Notes Payable | Payment in Kind ("PIK")
Line Of Credit Facility [Line Items]
Interest Rate				12.00%			12.00%
Loan outstanding balance			$ 2,900,000		$ 6,300,000	$ 2,900,000
Solar Asset Backed Securities Class A
Line Of Credit Facility [Line Items]
Aggregate amount of debt	$ 100,000,000
Solar Asset Backed Securities Class B
Line Of Credit Facility [Line Items]
Aggregate amount of debt	11,000,000
Asset Backed Securities
Line Of Credit Facility [Line Items]
Secured Borrowings Assets Carrying Amount					$ 190,200,000
Debt instrument discount rate					0.08%
Solar energy systems, gross					$ 119,700,000
Repayment of lease obligations	$ 88,900,000				88,900,000
Net of fees from proceeds from debt instrument					$ 7,300,000