Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions			1 Months Ended	12 Months Ended
	Aug. 08, 2018	May 04, 2018	Jan. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2018
Other Commitments [Line Items]
Letters of credit outstanding, amount				$ 9.7	$ 16.4
Minimum
Other Commitments [Line Items]
Letter of credit, fee percentage				2.50%	2.50%
Maximum
Other Commitments [Line Items]
Letter of credit, fee percentage				3.25%	3.25%
Settled litigation | Slovin et al. v. Sunrun Inc. and Clean Energy Experts, LLC
Other Commitments [Line Items]
Settlement amount, accrual						$ 5.5
Settled litigation | Cohen, et al. v. Sunrun Inc., et al.
Other Commitments [Line Items]
Settlement amount, accrual		$ 1.9
Settlement amount		32.0
Settlement amount, funded by insurers		$ 30.1
Settled litigation | Fink, et al. v. Sunrun Inc., et al.
Other Commitments [Line Items]
Settlement amount	$ 2.5
Photovoltaic Modules
Other Commitments [Line Items]
Purchase commitment			$ 135.4