Derivative Financial Instruments (Schedule Of Derivative Gains And Losses In The Statements Of Operations) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Not Designated As Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income	$ 10,232	$ 4,158	$ 6,355
Interest Rate Contracts [Member] | Interest Expense [Member] | Fair Value Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income	4,470	7,103	7,022
Interest Rate Contracts [Member] | Other Comprehensive Income (Loss) [Member] | Cash Flow Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Other Comprehensive Income (Loss)	1,139	(220)	(918)
Interest Rate Contracts [Member] | Other Revenue [Member] | Not Designated As Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income	1,232	(457)	(1,446)
Equity Contracts [Member] | Net Realized Investment Gains [Member] | Not Designated As Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income	$ 9,000	$ 4,615	$ 7,801