Loans and Leases (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	$ 98,700	$ 124,800
Proceeds from Sale of Loans Receivable	1,040,000	1,050,000
Nonaccruing	120,306	191,483
Loans and leases greater than 90 days and accruing	6,925	5,862
Financing Receivable, Recorded Investment, Nonaccrual Status, Remaining Discount	40,436	64,727
Portfolio Loans
Financing Receivable, Recorded Investment [Line Items]
Proceeds from Sale of Loans Receivable		7,600
Non-PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status, Remaining Discount	11,428	19,473
Non-PCI Loans \| Commercial
Financing Receivable, Recorded Investment [Line Items]
Nonaccruing	35,287	43,322
Loans and leases greater than 90 days and accruing	5,431	4,312
PCD Loans
Financing Receivable, Recorded Investment [Line Items]
Nonaccruing	29,616	54,939
Loans and leases greater than 90 days and accruing	543	355
Financing Receivable, Recorded Investment, Nonaccrual Status, Remaining Discount	29,008	45,254
Non-PCD Loans
Financing Receivable, Recorded Investment [Line Items]
Net deferred fees on non-PCI loans	31,785	50,217
Non-PCD Loans \| Other Portfolio
Financing Receivable, Recorded Investment [Line Items]
Net deferred fees on non-PCI loans	16,903	9,153
Non-PCD Loans \| SBA-PPP
Financing Receivable, Recorded Investment [Line Items]
Net deferred fees on non-PCI loans	14,882	41,064
Customer Concentration Risk \| Medical Dental And Related Field Borrowers \| Loans Receivable To Borrowers In Medical, Dental Or Related Fields \| Loans Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans in the medical, dental or related field	$ 7,090,000	$ 5,540,000
Loan concentration percentage	21.90%	16.90%
Geographic Concentration Risk \| Loans Receivable Secured By Real Estate Collateral \| Loans Receivable \| NORTH CAROLINA
Financing Receivable, Recorded Investment [Line Items]
Loan concentration percentage		35.90%
Geographic Concentration Risk \| Loans Receivable Secured By Real Estate Collateral \| Loans Receivable \| SOUTH CAROLINA
Financing Receivable, Recorded Investment [Line Items]
Loan concentration percentage		15.60%
Federal Home Loan Bank of Atlanta
Financing Receivable, Recorded Investment [Line Items]
Loans Pledged as Collateral	$ 14,507,109	$ 12,157,153
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	9,563,947	8,637,844
Advances from Federal Home Loan Banks	644,659	652,675
Federal Home Loan Bank Advances, Current Borrowing Capacity	8,919,288	7,985,169
Federal Reserve Bank
Financing Receivable, Recorded Investment [Line Items]
Loans Pledged as Collateral	4,806,443	4,104,866
Federal Reserve Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	3,950,649	3,321,762
Advances from Federal Home Loan Banks	0	0
Federal Home Loan Bank Advances, Current Borrowing Capacity	$ 3,950,649	$ 3,321,762

Carrying amount of total receivables of a designated industry disclosed as a concentration risk.

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