Debt - Credit Facility (Details) - Maximum [Member]	Sep. 30, 2017
CERP \| Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Leverage Ratio For Line Of Credit Facility	8.00
CGP \| Term Loan [Member] \| Secured Debt [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Line of Credit Facility [Line Items]
Leverage Ratio For Line Of Credit Facility	6.00

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