Commitments and Contingencies Contingencies (Details) $ in Millions	Jul. 31, 2020 USD ($)
Loss Contingencies [Line Items]
Loss Contingency, Amount Sought by Counterparty	$ 49
Loss Contingency, Amount Withheld by Counterparty	$ 50

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration