Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in operating cash flows from change in method of presentation to daily transactional activity		$ 67.0
Net cash flows from operating activities	$ 181.1	156.3
IPL [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in operating cash flows from change in method of presentation to daily transactional activity		67.0
Net cash flows from operating activities	$ 76.7	$ 1.8