Derivative Assets And Collateral Received (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Gross amounts of recognized assets	$ 114,348	$ 81,634
Derivative assets not subject to master netting agreements	19,700	10,200
Derivatives, Interest Rate Contracts | Subject to Master Netting Agreements
Derivative [Line Items]
Gross amounts of recognized assets	94,611	71,458
Gross amounts offset in the Statement of Condition	0	0
Net amounts of assets presented in the Statement of Condition	94,611	71,458
Derivative liabilities available for offset	(11,477)	(17,278)
Collateral Received	(26,901)	(33,370)
Net amount	$ 56,233	$ 20,810