Statements of Consolidated Cash Flows (Parentheticals) - Assets Held-for-sale - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash presented within assets held for sale at beginning of period	$ 0	$ 0	$ 0
Cash presented within assets held for sale at end of period	$ 0	$ 0	$ 0

Amount classified as cash and cash equivalents attributable to disposal group held for sale or disposed of.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant