Fair Value (Schedule Of Assets And Liabilities Measured At Fair Value By Class On A Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	$ 14,737,000	$ 15,161,000
Trading account, at fair value	106,000	148,000
Assets, Fair Value Disclosure	15,619,000	16,069,000
Securities sold, not yet purchased	85,000	95,000
Financial and Nonfinancial Liabilities, Fair Value Disclosure	219,000	237,000
US Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	13,425,000	13,731,000
Available-for-sale Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	1,291,000	1,334,000
Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	21,000	24,000
Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	4,000	9,000
Other liabilities	2,000	7,000
Mutual Funds And Stock Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities		72,000
Bank-owned life insurance [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments	516,000	507,000
Private Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments	102,000	95,000
Assets, Fair Value Disclosure	1,000	1,000
Interest-Only-Strip [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	18,000	18,000
Derivative Interest Rate Related And Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	1,000	1,000
Other liabilities	1,000
Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	40,000	28,000
Other liabilities	36,000	33,000
Warranty, Rights and Obligations, Fair Value Option [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	95,000	102,000
Other liabilities	95,000	102,000
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	40,000	96,000
Trading account, at fair value	14,000
Other assets		102,000
Assets, Fair Value Disclosure	153,000	207,000
Securities sold, not yet purchased	85,000	95,000
Financial and Nonfinancial Liabilities, Fair Value Disclosure	182,000	204,000
Level 1 [Member] | US Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	40,000	25,000
Level 1 [Member] | Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	4,000	9,000
Other liabilities	2,000	7,000
Level 1 [Member] | Mutual Funds And Stock Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities		71,000
Level 1 [Member] | Private Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments
Assets, Fair Value Disclosure	0	0
Level 1 [Member] | Warranty, Rights and Obligations, Fair Value Option [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	95,000
Other liabilities	95,000	102,000
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	14,697,000	15,065,000
Trading account, at fair value	92,000	148,000
Assets, Fair Value Disclosure	15,346,000	15,749,000
Securities sold, not yet purchased	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	37,000	33,000
Level 2 [Member] | US Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	13,385,000	13,706,000
Level 2 [Member] | Available-for-sale Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	1,291,000	1,334,000
Level 2 [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	21,000	24,000
Level 2 [Member] | Mutual Funds And Stock Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities		1,000
Level 2 [Member] | Bank-owned life insurance [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments	516,000	507,000
Level 2 [Member] | Private Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments
Assets, Fair Value Disclosure	0	0
Level 2 [Member] | Derivative Interest Rate Related And Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	1,000	1,000
Other liabilities	1,000
Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	40,000	28,000
Other liabilities	36,000	33,000
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	0	0
Assets, Fair Value Disclosure	120,000	113,000
Securities sold, not yet purchased	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | US Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	0	0
Fair Value, Inputs, Level 3 [Member] | Available-for-sale Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities
Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities
Fair Value, Inputs, Level 3 [Member] | Private Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments	102,000	95,000
Assets, Fair Value Disclosure	1,000	1,000
Fair Value, Inputs, Level 3 [Member] | Interest-Only-Strip [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	$ 18,000	$ 18,000