Borrowings (Short-Term Borrowings) (Details) - Federal Funds Purchased And Repurchase Agreements [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Short-term Debt [Line Items]
Year End Weighted Rate	0.80%	0.90%	0.80%
Average Weighted Rate	1.60%	1.30%	0.70%
Average Balance Outstanding	$ 1,822,098	$ 1,514,144	$ 1,462,387
Maximum Outstanding at any Month End	2,394,294	1,981,761	1,984,071
Balance at December 31	$ 1,850,772	$ 1,956,389	$ 1,507,138