Commitments and Contingencies Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Loss Contingencies [Line Items]
Operating risk loss	$ 3,624	$ 4,271	$ 9,290
Residential mortgage principal balance repurchase request received	543
Residential mortgage principal balance FHLB credit enhancement	126,000
Commitments to extend credit, overdraft protection	330,600
Residential mortgage repurchase reserves FHLB credit enhancement	1,800	2,300
Reserve for Off-balance Sheet Activities
Loss Contingencies [Line Items]
Valuation allowances and reserves	414,258	414,769
Reserve for Off-balance Sheet Activities | Total commitments to extend credit
Loss Contingencies [Line Items]
Valuation allowances and reserves	5,784,138	4,822,363
Reserve for Off-balance Sheet Activities | Total commitments to extend credit | Scenario, Previously Reported
Loss Contingencies [Line Items]
Valuation allowances and reserves		4,400,000
Reserve for Off-balance Sheet Activities | Commercial – industrial, financial and agricultural
Loss Contingencies [Line Items]
Valuation allowances and reserves	3,518,960	2,972,105
Reserve for Off-balance Sheet Activities | Commercial – industrial, financial and agricultural | Scenario, Previously Reported
Loss Contingencies [Line Items]
Valuation allowances and reserves		2,700,000
Reserve for Off-balance Sheet Activities | Commercial Loans, Commerical Mortgages, Constructions Loans
Loss Contingencies [Line Items]
Valuation allowances and reserves	965,116	558,662
Reserve for Off-balance Sheet Activities | Commercial Loans, Commerical Mortgages, Constructions Loans | Scenario, Previously Reported
Loss Contingencies [Line Items]
Valuation allowances and reserves		400,000
Reserve for Off-balance Sheet Activities | Residential Mortgage
Loss Contingencies [Line Items]
Valuation allowances and reserves	$ 2,600	$ 3,200