Investments (Narrative) (Details) $ in Millions	3 Months Ended
Mar. 31, 2016 USD ($)
Schedule of Investments [Line Items]
Proceeds from liquidation of company-owned life insurance policies	$ 26
IPL [Member]
Schedule of Investments [Line Items]
Proceeds from liquidation of company-owned life insurance policies	$ 18

The net cash outflow or inflow for net proceeds and payments derived from carrying life insurance policies for which the entity is the beneficiary.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Name:	us-gaap_PaymentsForProceedsFromLifeInsurancePolicies
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration