Fair Value Measurements - Schedule of Fair Value Measurement of Debt Instrument (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	$ 468,816	$ 239,251
Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	475,634	241,574
Line of Credit | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	133,294	48,597
Line of Credit | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	133,294	48,597
Non Bank Term Loans | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value		3,138
Non Bank Term Loans | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value		3,853
Syndicated Term Loans | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	162,079	124,571
Syndicated Term Loans | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	162,079	124,571
Bank Term Loan | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	31,520	33,382
Bank Term Loan | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	34,917	35,653
Notes Payable | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	32,225	29,563
Notes Payable | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	32,166	$ 28,900
Solar Asset-Backed Notes | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	109,698
Solar Asset-Backed Notes | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	$ 113,178