Fair Value Measurements (Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Assets
Assets from price risk management	$ 728.9	$ 500.7
SPH units	2.2	2.1
Total assets at fair value	731.1	502.8
Netting Agreements	(607.4)	(455.0)
Collateral/Margin Received or Paid	(79.4)	(18.5)
Fair Value	42.1	27.2
Total assets at fair value	44.3	29.3
Liabilities
Liabilities from price risk management	713.2	519.1
Total liabilities at fair value	713.2	519.1
Netting Agreements	(607.4)	(455.0)
Collateral/Margin Received or Paid	8.8	12.2
Fair Value	114.6	76.3
Total liabilities at fair value		76.3
Level 1
Assets
Assets from price risk management	33.3	20.2
SPH units	2.2	2.1
Total assets at fair value	35.5	22.3
Liabilities
Liabilities from price risk management	26.9	25.1
Total liabilities at fair value	26.9	25.1
Level 2
Assets
Assets from price risk management	695.6	480.5
SPH units	0.0	0.0
Total assets at fair value	695.6	480.5
Liabilities
Liabilities from price risk management	686.3	494.0
Total liabilities at fair value	686.3	494.0
Level 3
Assets
Assets from price risk management	0.0	0.0
SPH units	0.0	0.0
Total assets at fair value	0.0	0.0
Liabilities
Liabilities from price risk management	0.0	0.0
Total liabilities at fair value	$ 0.0	$ 0.0