Contingencies, Guarantees and Indemnifications (Details) $ in Millions	Mar. 31, 2018 USD ($)
Guarantees to third parties primarily related to former subsidiaries and joint ventures
Guarantees and Indemnifications
Maximum exposure under guarantees	$ 148.0
Guarantees related to P-Caps contingent funding agreements
Guarantees and Indemnifications
Maximum exposure under guarantees	$ 750.0

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12069-110248

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant