Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.

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

Subsequent Event- Additional Information (Detail) - PGS and OPC [Member]	Feb. 07, 2017	Jun. 28, 2016
Subsequent Event [Line Items]
Decrease bottom return on equity		9.25%
Subsequent Event [Member]
Subsequent Event [Line Items]
Decrease bottom return on equity	9.25%