Summary of Significant Accounting Policies - Summary of Components of Benefit Obligation (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets, Noncurrent	$ 524.3	$ 1,230.8
Pension Plan [Member] | Defined Benefit Plans Income Loss [Member]
Components of Benefit Obligation Regulatory Asset	110.0	89.6
Other Postretirement Benefits Plan [Member] | Prior Service Cost [Member]
Components of Benefit Obligation Regulatory Asset	0.0	(3.6)
Other Postretirement Benefits Plan [Member] | Defined Benefit Plans Income Loss [Member]
Components of Benefit Obligation Regulatory Asset	9.7	23.2
Benefit obligations regulatory asset [Member]
Regulatory Assets, Noncurrent	$ 119.7	$ 109.2