Summary Of Significant Accounting Policies (Recent Accounting Pronouncements) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred Tax Liabilities, Other Comprehensive Income	$ 590,250	$ 603,523
Operating Leases, Future Minimum Payments Due	305,907
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated Other Comprehensive Income (Loss)	300
Accounting Standards Update 2016-01 [Member] | Equity Securities [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated Other Comprehensive Income (Loss)	(2,600,000)
Deferred Tax Liabilities, Other Comprehensive Income	684,400
Accounting Standards Update 2018-02 [Domain]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained Earnings, Unappropriated	402,900
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	250,000
Operating Lease, Liability	$ 275,000