Fair Value Measurements, Fair Value Of Financial Instruments as Measured On a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2023		Mar. 31, 2023	Dec. 31, 2022		Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Assets: [Abstract]
Trading securities	$ 5,442,364			$ 4,464,161
Available for sale securities	11,938,523			11,493,860
Fair value option securities	212,321			296,590
Mortgage servicing rights	304,722		$ 299,803	277,608		$ 270,312	$ 209,563	$ 163,198
Derviative contracts, net of cash collateral, Assets, Fair value	353,037			880,343
Liabilities: [Abstract]
Derivative contracts, net of cash collateral, Liabilities, Fair Value	550,653			554,900
U.S. government securities [Member]
Assets: [Abstract]
Trading securities	46,994			9,823
Residential agency mortgage-backed securities [Member]
Assets: [Abstract]
Trading securities	5,334,372			4,406,848
Available for sale securities	6,114,202			5,814,496
Fair value option securities	212,321			296,590
Municipal securities [Member]
Assets: [Abstract]
Trading securities	49,595			21,484
Available for sale securities	491,715			624,500
U.S. Treasury [Member]
Assets: [Abstract]
Available for sale securities	901			898
Residential non-agency mortgage-backed securities [Member]
Assets: [Abstract]
Available for sale securities	699,178			577,576
Commercial agency mortgage-backed securities [Member]
Assets: [Abstract]
Available for sale securities	4,632,054			4,475,917
Other debt securities [Member]
Assets: [Abstract]
Trading securities	11,403			26,006
Available for sale securities	473			473
Fair Value, Recurring [Member]
Assets: [Abstract]
Trading securities	5,442,364			4,464,161
Available for sale securities	11,938,523			11,493,860
Residential mortgage loans held for sale	94,820	[1]		75,272	[2]
Mortgage servicing rights	304,722	[3]		277,608	[4]
Derviative contracts, net of cash collateral, Assets, Fair value	353,037			880,343
Liabilities: [Abstract]
Derivative contracts, net of cash collateral, Liabilities, Fair Value	550,653			554,900
Fair Value, Recurring [Member] | U.S. government securities [Member]
Assets: [Abstract]
Trading securities	46,994			9,823
Fair Value, Recurring [Member] | Residential agency mortgage-backed securities [Member]
Assets: [Abstract]
Trading securities	5,334,372			4,406,848
Available for sale securities	6,114,202			5,814,496
Fair value option securities	212,321			296,590
Fair Value, Recurring [Member] | Municipal securities [Member]
Assets: [Abstract]
Trading securities	49,595			21,484
Available for sale securities	491,715			624,500
Fair Value, Recurring [Member] | Other trading securities
Assets: [Abstract]
Trading securities	11,403			26,006
Fair Value, Recurring [Member] | U.S. Treasury [Member]
Assets: [Abstract]
Available for sale securities	901			898
Fair Value, Recurring [Member] | Residential non-agency mortgage-backed securities [Member]
Assets: [Abstract]
Available for sale securities	699,178			577,576
Fair Value, Recurring [Member] | Commercial agency mortgage-backed securities [Member]
Assets: [Abstract]
Available for sale securities	4,632,054			4,475,917
Fair Value, Recurring [Member] | Other debt securities [Member]
Assets: [Abstract]
Available for sale securities	473			473
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets: [Abstract]
Trading securities	4,963			4,970
Available for sale securities	901			898
Residential mortgage loans held for sale	0	[1]		0	[2]
Mortgage servicing rights	0	[3]		0	[4]
Derviative contracts, net of cash collateral, Assets, Fair value	2,506			2,110
Liabilities: [Abstract]
Derivative contracts, net of cash collateral, Liabilities, Fair Value	4			16
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. government securities [Member]
Assets: [Abstract]
Trading securities	4,963			4,970
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Residential agency mortgage-backed securities [Member]
Assets: [Abstract]
Trading securities	0			0
Available for sale securities	0			0
Fair value option securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Municipal securities [Member]
Assets: [Abstract]
Trading securities	0			0
Available for sale securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other trading securities
Assets: [Abstract]
Trading securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasury [Member]
Assets: [Abstract]
Available for sale securities	901			898
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Residential non-agency mortgage-backed securities [Member]
Assets: [Abstract]
Available for sale securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial agency mortgage-backed securities [Member]
Assets: [Abstract]
Available for sale securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other debt securities [Member]
Assets: [Abstract]
Available for sale securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets: [Abstract]
Trading securities	5,437,401			4,459,191
Available for sale securities	11,937,149			11,492,489
Residential mortgage loans held for sale	87,572	[1]		68,054	[2]
Mortgage servicing rights	0	[3]		0	[4]
Derviative contracts, net of cash collateral, Assets, Fair value	350,531			878,233
Liabilities: [Abstract]
Derivative contracts, net of cash collateral, Liabilities, Fair Value	550,649			554,884
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. government securities [Member]
Assets: [Abstract]
Trading securities	42,031			4,853
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Residential agency mortgage-backed securities [Member]
Assets: [Abstract]
Trading securities	5,334,372			4,406,848
Available for sale securities	6,114,202			5,814,496
Fair value option securities	212,321			296,590
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal securities [Member]
Assets: [Abstract]
Trading securities	49,595			21,484
Available for sale securities	491,715			624,500
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other trading securities
Assets: [Abstract]
Trading securities	11,403			26,006
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Treasury [Member]
Assets: [Abstract]
Available for sale securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Residential non-agency mortgage-backed securities [Member]
Assets: [Abstract]
Available for sale securities	699,178			577,576
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial agency mortgage-backed securities [Member]
Assets: [Abstract]
Available for sale securities	4,632,054			4,475,917
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other debt securities [Member]
Assets: [Abstract]
Available for sale securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets: [Abstract]
Trading securities	0			0
Available for sale securities	473			473
Residential mortgage loans held for sale	7,248	[1]		7,218	[2]
Mortgage servicing rights	304,722	[3]		277,608	[4]
Derviative contracts, net of cash collateral, Assets, Fair value	$ 0			$ 0
Liquidity Discount on Mortgage Loans Qualifying for Sale to US Govt Agencies	78.99%			77.55%
Liabilities: [Abstract]
Derivative contracts, net of cash collateral, Liabilities, Fair Value	$ 0			$ 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. government securities [Member]
Assets: [Abstract]
Trading securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Residential agency mortgage-backed securities [Member]
Assets: [Abstract]
Trading securities	0			0
Available for sale securities	0			0
Fair value option securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Municipal securities [Member]
Assets: [Abstract]
Trading securities	0			0
Available for sale securities				0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other trading securities
Assets: [Abstract]
Trading securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Treasury [Member]
Assets: [Abstract]
Available for sale securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Residential non-agency mortgage-backed securities [Member]
Assets: [Abstract]
Available for sale securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial agency mortgage-backed securities [Member]
Assets: [Abstract]
Available for sale securities	0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other debt securities [Member]
Assets: [Abstract]
Available for sale securities	$ 473			$ 473

[1] Residential mortgage loans held for sale measured at fair value on a recurring basis using significant unobservable inputs (Level 3) consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards and are valued at 78.99% of the unpaid principal balance.

[2] Residential mortgage loans held for sale measured at fair value on a recurring basis using significant unobservable inputs (Level 3) consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards and are valued at 77.55% of the unpaid principal balance.

[3] A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 5, Mortgage Banking Activities.3See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in asset and liability positions that were valued based on quoted prices in active markets for identical instruments (Level 1) are primarily exchange-traded interest rate derivative contracts held for trading purposes.

[4] A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 5, Mortgage Banking Activities.3See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in asset and liability positions that were valued based on quoted prices in active markets for identical instruments (Level 1) are primarily exchange-traded interest rate derivative contracts held for trading purposes.