Recent Accounting Pronouncements (Schedule of Impact of Adoption Reflected in Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Jan. 01, 2020	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Assets and Liabilities
Allowance for loan and lease losses	$ 240,662	$ 448,674	$ 191,251	$ 195,572	$ 194,514
Reserve for unfunded lending commitments	31,304	31,526	3,974
Total allowance for credit losses	271,966	480,200	195,225
Retained Earnings
Decrease to retained earnings		$ 1,211,878	$ 1,476,232
Implementation CECL [Member]
Assets and Liabilities
Allowance for loan and lease losses	49,411
Reserve for unfunded lending commitments	27,330
Total allowance for credit losses	76,741
Retained Earnings
Allowance for credit loss increase	76,741
Balance sheet reclassification	19,767
Total pretax impact	56,974
Income tax impact	(12,888)
Decrease to retained earnings	$ 44,086