Income Taxes (Reconciliation Of Provision For Income Taxes) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Consolidated tax provision at federal statutory rate	35.00%	35.00%	35.00%
State income tax provisions, net of federal income tax benefit	1.70%	(0.10%)	8.70%
Tax reserve adjustment	0.10%	0.60%	(0.30%)
Domestic production activities deduction		(1.90%)
Changes in certain deferred tax balances	(0.40%)	5.80%	0.80%
Goodwill impairment	(19.10%)
Federal research and development credit	0.10%	1.00%	1.50%
Non-deductible transaction costs			0.40%
Deferred Tax Remeasurement - 2017 Tax Reform	26.10%
All other, net	(0.10%)	(0.20%)	(0.30%)
Effective tax rate	43.40%	40.20%	45.80%