Receivables (Narrative) (Details) $ in Millions	Dec. 31, 2018 USD ($)
Accounts Receivable [Line Items]
Limit on cash proceeds to be received from third-party	$ 90.0
Maximum [Member]
Accounts Receivable [Line Items]
Limit on cash proceeds to be received from third-party	110.0
Receivables Sold [Member] \| IPL [Member]
Accounts Receivable [Line Items]
Available capacity	$ 0.0

The face amount of accounts receivable that will be sold to other entities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Name:	us-gaap_TradeReceivablesHeldForSaleAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant