Variable Interest Entities - Summary of VIEs (Detail)	3 Months Ended
	Mar. 31, 2016 USD ($) MW
Pilesgrove | Minimum | Solar Renewable Energy Credit Hedge
Variable Interest Entity [Line Items]
Renewable Energy Credit	3 years
Pilesgrove | Maximum | Solar Renewable Energy Credit Hedge
Variable Interest Entity [Line Items]
Renewable Energy Credit	4 years
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure
Variable Interest Entity [Line Items]
Percentage of variable interests	50.00%
Variable Interest Entity, Not Primary Beneficiary | Copper Mountain Solar 3 | Nevada
Variable Interest Entity [Line Items]
Generating Capacity (MWs AC) | MW	128
Power Purchase Agreement Term (in Years)	20 years
Year of Initial Investment	2014
Maximum exposure to loss	$ 183,000,000
Variable Interest Entity, Not Primary Beneficiary | Panoche Valley | California
Variable Interest Entity [Line Items]
Generating Capacity (MWs AC) | MW	124
Power Purchase Agreement Term (in Years)	20 years
Year of Initial Investment	2015
Maximum exposure to loss	$ 133,000,000
Variable Interest Entity, Not Primary Beneficiary | Mesquite Solar 1 | Arizona
Variable Interest Entity [Line Items]
Generating Capacity (MWs AC) | MW	83
Power Purchase Agreement Term (in Years)	20 years
Year of Initial Investment	2013
Maximum exposure to loss	$ 99,000,000
Variable Interest Entity, Not Primary Beneficiary | Copper Mountain Solar 2 | Nevada
Variable Interest Entity [Line Items]
Generating Capacity (MWs AC) | MW	75
Power Purchase Agreement Term (in Years)	25 years
Year of Initial Investment	2013
Maximum exposure to loss	$ 82,000,000
Variable Interest Entity, Not Primary Beneficiary | California Solar | California
Variable Interest Entity [Line Items]
Generating Capacity (MWs AC) | MW	55
Power Purchase Agreement Term (in Years)	25 years
Year of Initial Investment	2012
Maximum exposure to loss	$ 65,000,000
Variable Interest Entity, Not Primary Beneficiary | Broken Bow II | Nebraska
Variable Interest Entity [Line Items]
Generating Capacity (MWs AC) | MW	38
Power Purchase Agreement Term (in Years)	25 years
Year of Initial Investment	2014
Maximum exposure to loss	$ 54,000,000
Variable Interest Entity, Not Primary Beneficiary | Pilesgrove | New Jersey
Variable Interest Entity [Line Items]
Generating Capacity (MWs AC) | MW	9
Year of Initial Investment	2010
Maximum exposure to loss	$ 26,000,000
Variable Interest Entity, Primary Beneficiary | Texas Solar 4
Variable Interest Entity [Line Items]
Percentage of variable interests	80.00%
VIEs, noncontrolling interest	$ 8,000,000
Variable Interest Entity, Primary Beneficiary | Texas Solar 4 | Texas
Variable Interest Entity [Line Items]
Generating Capacity (MWs AC) | MW	32
Power Purchase Agreement Term (in Years)	25 years
Year of Initial Investment	2014
Maximum exposure to loss	$ 15,000,000