Variable Interest Entities - Summary of VIEs (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2016 USD ($) MW
Variable Interest Entity, Not Primary Beneficiary | Copper Mountain Solar 3 | Nevada
Variable Interest Entity [Line Items]
Generating Capacity Owned (MW AC) | MW		128
Power Purchase Agreement Term in Years		20 years
Maximum Exposure to Loss		$ 179,000,000
Variable Interest Entity, Not Primary Beneficiary | Mesquite Solar 1 | Arizona
Variable Interest Entity [Line Items]
Generating Capacity Owned (MW AC) | MW		83
Power Purchase Agreement Term in Years		20 years
Maximum Exposure to Loss		$ 108,000,000
Variable Interest Entity, Not Primary Beneficiary | Copper Mountain Solar 2 | Nevada
Variable Interest Entity [Line Items]
Generating Capacity Owned (MW AC) | MW		75
Power Purchase Agreement Term in Years		25 years
Maximum Exposure to Loss		$ 84,000,000
Variable Interest Entity, Not Primary Beneficiary | California Solar | California
Variable Interest Entity [Line Items]
Generating Capacity Owned (MW AC) | MW		55
Power Purchase Agreement Term in Years		25 years
Maximum Exposure to Loss		$ 69,000,000
Variable Interest Entity, Not Primary Beneficiary | Broken Bow II | Nebraska
Variable Interest Entity [Line Items]
Generating Capacity Owned (MW AC) | MW		38
Power Purchase Agreement Term in Years		25 years
Maximum Exposure to Loss		$ 48,000,000
Variable Interest Entity, Primary Beneficiary | Texas Solar 4
Variable Interest Entity [Line Items]
Percentage of variable interests	80.00%	80.00%
Maximum exposure for consolidated investments		$ 7,000,000
Variable Interest Entity, Primary Beneficiary | Texas Solar 4 | Texas
Variable Interest Entity [Line Items]
Generating Capacity Owned (MW AC) | MW		32
Power Purchase Agreement Term in Years		25 years
Maximum Exposure to Loss		$ 47,000,000
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure
Variable Interest Entity [Line Items]
Percentage of variable interests		50.00%