Operations and Significant Accounting Policies - Subsequent Events (Details) - Subsequent Event [Member] $ in Millions	Feb. 08, 2019 USD ($)
Subsequent Event [Line Items]
Cash Purchase Price on the Sale of U.S. Water Services	$ 270
Estimated Gain on the Sale of U.S. Water Services	$ 10

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