Commitments and Contingencies (Schedule for Unfunded Commitments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Unused Commitments to Extend Credit	$ 6,755,563	$ 6,379,941
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance		2,506	$ 2,362
Provision			144
Ending balance			2,506
Accounting Standards Update 2016-13 [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	0	0
Ending balance	9,139	0	0
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	2,367	2,506
Provision	1,249	(139)
Ending balance	$ 12,755	$ 2,367	$ 2,506