Business Combination - Assets Acquired and Liabilities Assumed (Details) - NRG South Central $ in Thousands	Feb. 04, 2019 USD ($)
Current assets
Cash and cash equivalents	$ 146,494
Customer and other accounts receivable	48,401
Energy risk management assets	4,193
Other current assets	10,000
Non-current assets
Property, plant, and equipment, net	727,906
Prepayments	36,222
Restricted cash and cash equivalents	707
Intangible assets	102,500
Other deferred charges	132
Total assets acquired	1,124,274
Current liabilities
Accounts payable	35,456
Taxes payable	723
Energy risk management liabilities	242
Other current liabilities	14,243
Non-current liabilities
Accumulated deferred federal and state income taxes, net	6,744
Deferred lease revenue	61,900
Intangible liabilities	31,900
Asset retirement obligations	10,789
Operating lease liability	107
Total liabilities assumed	162,104
Total purchase price consideration	962,170
Fuel inventory
Current assets
Inventory	22,060
Materials and supplies
Current assets
Inventory	$ 25,659