Derivative Instruments (Change In Fair Value Of Derivative Instruments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Non-hedging interest rate derivatives: | Derivative Assets | Other Income
Derivatives, Fair Value [Line Items]
Change in Fair Value	$ (1,897)	$ 2,244	$ (3,315)	$ (15,846)
Non-hedging interest rate derivatives: | Derivative Assets | Other Expense
Derivatives, Fair Value [Line Items]
Change in Fair Value	6	0	30	0
Non-hedging interest rate derivatives: | Derivative Liabilities | Other Income
Derivatives, Fair Value [Line Items]
Change in Fair Value	1,897	(2,317)	3,315	16,181
Derivatives designated as hedges of fair value: | Derivative Assets | Other Income
Derivatives, Fair Value [Line Items]
Change in Fair Value	(3)	0	6	0
Derivatives designated as hedges of fair value: | Derivative Liabilities | Other Income
Derivatives, Fair Value [Line Items]
Change in Fair Value	0	6	0	10
Hedged item - derivative asset | Derivatives designated as hedges of fair value: | Derivative Assets
Derivatives, Fair Value [Line Items]
Change in Fair Value	$ 0	$ (45)	$ 3	$ 119