Derivatives - Derivative Assets And Collateral Received (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Gross amounts of recognized assets	$ 118,128	$ 81,475
Derivative assets not subject to master netting agreements	37,100	28,900
Derivatives, interest rate contracts
Derivative [Line Items]
Collateral received	(68,887)	(39,637)
Net amount	35	180
Derivatives, interest rate contracts | Subject to Master Netting Agreements
Derivative [Line Items]
Gross amounts of recognized assets	81,003	52,562
Derivative liabilities available for offset	0	0
Net amount	81,003	52,562
Derivative liabilities available for offset	$ (12,081)	$ (12,745)