Income Taxes (Reconciliation Of Provision For Income Taxes) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Taxes [Abstract]
Consolidated tax provision at federal statutory rate (in hundredths)	21.00%	21.00%	21.00%	21.00%
State income tax provisions, net of federal income tax benefit (in hundredths)	(0.70%)	0.80%	1.30%	0.40%
Remeasurement of certain deferred tax balances (in hundredths)				0.90%
Tax reserve adjustment (in hundredths)	(0.10%)	0.50%		0.50%
Changes in certain deferred tax balances (in hundredths)	(0.60%)	(10.40%)	(1.80%)	(8.60%)
Goodwill impairment (in hundreths)	(15.90%)	(10.40%)	(10.70%)	(10.30%)
Loss on disposal of Northwest Operations (in hundreths)	1.80%		(1.20%)
Shared-based payments (in hundreths)			(0.10%)	(0.80%)
Federal research and development tax credit (in hundreths)	0.30%	(1.00%)		(1.00%)
All other, net (in hundredths)	(0.20%)	0.40%		0.40%
Effective tax rate (in hundredths)	5.60%	0.90%	8.50%	2.50%