Other Commitments and Contingencies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Subsequent Event [Line Items]
Intercompany Agreements, Description	P3Y
Debt Service Coverage Ratio	1.25
Time to cure ratio	5 days
Ratio based on average number of prior quarters	6
Funds from operations interest coverage ratio minimum times	2
Total debt to capital maximum	65
Number Of Years to Collect Benefits	20 years
Total purchase obligations for 2018	$ 60,735
Total purchase obligations for 2019 - 2020	72,123
Total purchase obligations for 2021 - 2022	60,049
Total purchase obligations thereafter	201,131
Aggregate guaranteed amount	37,000
Guarantor Obligations, Current Carrying Value	24,700
Guarantor Obligations, Current Carrying Value, PESCO	16,300
Amount of letter of credit to our current primary insurance company	$ 5,400
Florida Natural Gas Distribution and Eight Flags [Member]
Subsequent Event [Line Items]
Number of Years for Asset Management Agreement	10 years