Accumulated Other Comprehensive Income (Summary Of Accumulated Other Comprehensive Income, Net Of Taxes) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income [Line Items]
Net unrealized gains on investments	$ 758,616	$ 998,151
Net unrealized foreign exchange losses	(5,095)	(3,168)
Net unrealized losses on derivative instruments	(160)
Total accumulated other comprehensive income	671,579	912,421
Net Minimum Pension Liability [Member]
Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss) related to defined benefit pension and other postretirement plans, net of tax	(82,596)	(83,537)
Net Postretirement Benefit [Member]
Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss) related to defined benefit pension and other postretirement plans, net of tax	$ 814	$ 975