Derivatives (Assets And Collateral Received) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Gross amounts of recognized assets	$ 122,056	$ 81,634
Gross amounts not offset in the Statements of Condition
Derivative assets not subject to master netting agreements	19,200	10,200
Derivatives, interest rate contracts
Derivative [Line Items]
Gross amounts of recognized assets	102,852	71,458
Gross amounts offset in the Statements of Condition	0	0
Net amounts of assets presented in the Statements of Condition	102,852	71,458
Gross amounts not offset in the Statements of Condition
Derivative assets available for offset	(13,490)	(17,278)
Collateral pledged	(89,317)	(51,271)
Net amount	$ 45	$ 2,909