Derivatives - Derivative Assets and Collateral Received (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Gross amounts of recognized assets	$ 599,445	$ 182,984
Derivative liabilities available for offset	0	0
Net amount	599,445	182,984
Derivative liabilities available for offset	(9,180)	(18,896)
Collateral received	(361,087)	(145,334)
Net amount	229,178	18,754
Derivative assets not subject to master netting agreements	300	100
Derivatives, interest rate contracts
Derivative [Line Items]
Gross amounts of recognized assets	564,037	162,344
Derivative liabilities available for offset	0	0
Net amount	564,037	162,344
Derivative liabilities available for offset	(2,253)	(5,604)
Collateral received	(348,497)	(143,334)
Net amount	213,287	13,406
Forward Contracts
Derivative [Line Items]
Gross amounts of recognized assets	35,408	20,640
Derivative liabilities available for offset	0	0
Net amount	35,408	20,640
Derivative liabilities available for offset	(6,927)	(13,292)
Collateral received	(12,590)	(2,000)
Net amount	$ 15,891	$ 5,348