Estimated Fair Values (Assets And Liabilities Carried At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	$ 6,557,580	$ 6,861,293
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	6,557,580	6,861,293
Loans held for sale	84,795	59,766
Interest rate swaps accounted for as cash flow hedges		1,429
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	23,197	1,668
Loans held for sale	0	0
Interest rate swaps accounted for as cash flow hedges		0
Fair Value, Measurements, Recurring | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	6,534,383	6,859,625
Loans held for sale	84,795	59,766
Interest rate swaps accounted for as cash flow hedges		1,429
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Loans held for sale	0	0
Interest rate swaps accounted for as cash flow hedges		0
Fair Value, Measurements, Recurring | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	1,541,479	1,674,882
Fair Value, Measurements, Recurring | U.S. Treasury | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | U.S. Treasury | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	1,541,479	1,674,882
Fair Value, Measurements, Recurring | U.S. Treasury | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Government Agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	355,545	498,660
Fair Value, Measurements, Recurring | Government Agency | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Government Agency | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	355,545	498,660
Fair Value, Measurements, Recurring | Government Agency | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Mortgage Backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	4,535,831	4,668,198
Fair Value, Measurements, Recurring | Mortgage Backed Securities | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Mortgage Backed Securities | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	4,535,831	4,668,198
Fair Value, Measurements, Recurring | Mortgage Backed Securities | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Other Debt Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	1,950	2,160
Fair Value, Measurements, Recurring | Other Debt Obligations | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Other Debt Obligations | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	1,950	2,160
Fair Value, Measurements, Recurring | Other Debt Obligations | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	81,390	8,893
Fair Value, Measurements, Recurring | Equity Securities | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	23,197	1,668
Fair Value, Measurements, Recurring | Equity Securities | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	58,193	7,225
Fair Value, Measurements, Recurring | Equity Securities | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	41,385	8,500
Fair Value, Measurements, Recurring | Corporate Bonds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Corporate Bonds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	41,385	8,500
Fair Value, Measurements, Recurring | Corporate Bonds | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	$ 0	$ 0