Financial Instruments And Investments Transfers Between Levels (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value, Assets, Level 1 to Level 2 Transfers, Description	no	no	no	no	no	no
Fair Value, Assets, Level 2 to Level 1 Transfers, Description	no	no	no	no	no	no
Fair Value, Asset, Level 3 Purchases, (Sales), Issuances, (Settlements)	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0