Amount of gain (loss) recognized in settlement of litigation and insurance claims. Excludes claims within an insurance entity's normal claims settlement process.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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

Commitments and Contingencies (Details) $ in Millions	1 Months Ended			3 Months Ended
Commitments and Contingencies (Details) $ in Millions	Mar. 31, 2017 USD ($)	Aug. 31, 2014 USD ($)	Jul. 31, 2013 defendant	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Commitments and Contingencies
Gain on litigation settlement		$ 6.1		$ 17.5	$ 0.0
Additional settlement payment received	$ 17.5
Judicial ruling \| Board of Commissioners for the Southeast Louisiana Flood Protection Authority for New Orleans
Commitments and Contingencies
Number of energy companies sued (in defendant) \| defendant			100