Palo Verde Sale Leaseback Variable Interest Entities - Schedule of VIEs (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Palo Verde sale leaseback property plant and equipment, net of accumulated depreciation	$ 104,808	$ 105,775
Equity — Noncontrolling interests	130,663	125,790
APS
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Palo Verde sale leaseback property plant and equipment, net of accumulated depreciation	104,808	105,775
Equity — Noncontrolling interests	130,663	125,790
APS | Consolidation of VIEs
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Palo Verde sale leaseback property plant and equipment, net of accumulated depreciation	104,808	105,775
Equity — Noncontrolling interests	$ 130,663	$ 125,790