Note 5 - Derivatives - Interest Rate Swaps Outstanding (Details) - Rio Grande [Member] - Contingent Interest Rate Swaps [Member] $ in Millions	6 Months Ended
	Jun. 30, 2023 USD ($)
Initial Notional Amount	$ 86
Maturity Date	Mar. 28, 2049
Variable Interest Rate Received	3.20%
Maximum [Member]
Initial Notional Amount	$ 5,905