Income Taxes (Schedule Of Company's Actual Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Computed “expected” tax expense	$ 113,293	$ 150,461	$ 139,840
Tax-exempt interest, net of cost to carry	(11,502)	(20,295)	(20,033)
Effective Income Tax Rate Reconciliation, Contribution of Appreciated Securities, Amount	0	(10,864)	0
State and local income taxes, net of federal tax benefit	9,748	5,955	6,132
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	0	(6,753)	0
Effective Income Tax Rate Reconciliation, Share-based Award Payments, Amount	(3,928)	(6,613)	0
Other	(1,662)	(1,385)	(1,788)
Total income tax expense	$ 105,949	$ 110,506	$ 124,151