Derivatives (Offsetting of Derivatives) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Gross Amounts Recognized	$ 330,316	$ 107,816
Less: Master Netting Arrangements	(121,561)	(31,569)
Less: Cash collateral received or paid	(3,758)	(13,577)
Derivative asset, after netting	204,997	62,670
Less: Security Collateral Received	0	(13,975)
Net derivative assets	204,997	48,695
Derivative assets subject to master netting arrangements, gross amounts recognized	328,700	105,900
Contracts not subject to master netting arrangements, gross amounts recognized	1,600	2,000
Derivative, cash collateral received, including amount offset by fair value assets, and excess cash amount	3,800	15,800
Liabilities
Gross Amounts Recognized	256,528	118,305
Less: Master Netting Arrangements	(121,561)	(31,569)
Less: Cash collateral received/paid	(38,238)	(6,833)
Derivative liability, after netting	96,729	79,903
Less: Security Collateral Pledged	(79,619)	(11,231)
Net derivative liabilities	17,110	68,672
Derivative liability subject to master netting arrangements, gross amounts recognized	256,500	118,200
Contracts not subject to master netting arrangements, gross amounts recognized	20	102
Derivative, cash collateral posted against derivative liabilities, including amount offset the derivative fair value liabilities, and excess cash amount	$ 43,000	$ 8,400