Fair Value Measurements (Assets And Liabilities Measured On Nonrecurring Basis) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Assets:
Total Gains (Losses)	$ (122)	$ (447)	$ (44)
Fair Value, Nonrecurring [Member]
Assets:
Assets, fair value	$ 0	$ 0		$ 47,746
Total Gains (Losses)				(12,686)
Fair Value, Nonrecurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Assets, fair value				47,746
Fair Value, Nonrecurring [Member] | Property, Plant and Equipment [Member]
Assets:
Assets, fair value				47,746
Total Gains (Losses)				(12,686)
Fair Value, Nonrecurring [Member] | Property, Plant and Equipment [Member] | Carrying Value [Member]
Assets:
Assets, fair value				60,400
Fair Value, Nonrecurring [Member] | Property, Plant and Equipment [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Assets, fair value				$ 47,746