Fair Value Measurement - Schedule of Carrying Values and Fair Values of Debt Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	$ 949,275	$ 898,023
Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	951,918	897,996
Lines of Credit | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	526,300	489,200
Lines of Credit | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	526,300	489,200
Syndicated Term Loans | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	189,163	189,989
Syndicated Term Loans | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	189,165	189,989
Bank Term Loans | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	96,258	81,307
Bank Term Loans | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	95,450	80,542
Notes Payable | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	37,363	36,232
Notes Payable | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	36,404	35,396
Solar Asset-Backed Notes | Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	100,191	101,295
Solar Asset-Backed Notes | Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt Instrument, Fair Value	$ 104,599	$ 102,869