Fair Value Measurements, Fair Value Of Financial Instruments as Measured On a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Assets [Abstract]
Trading securities	$ 9,136,813		$ 4,707,975
Available for sale securities	13,157,817		13,050,665
Fair value option securities	43,770		114,982
Mortgage servicing rights	163,198		101,172		$ 201,886	$ 259,254
Derivative contracts, net of cash margin, Assets, Fair Value	1,097,297		810,688
Liabilities [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	275,625		405,779
U.S. government securities [Member]
Assets [Abstract]
Trading securities	23,610		9,183
Residential agency mortgage-backed securities [Member]
Assets [Abstract]
Trading securities	9,068,900		4,669,148
Available for sale securities	8,006,616		9,340,471
Fair value option securities	43,770		114,982
Municipal securities [Member]
Assets [Abstract]
Trading securities	25,783		19,172
Available for sale securities	508,365		167,979
U.S. Treasury [Member]
Assets [Abstract]
Available for sale securities	1,000		508
Residential non-agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	24,339		32,770
Commercial agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	4,617,025		3,508,465
Other debt securities [Member]
Assets [Abstract]
Trading securities	18,520		10,472
Available for sale securities	472		472
Fair Value, Recurring [Member]
Assets [Abstract]
Trading securities	9,136,813		4,707,975
Available for sale securities	13,157,817		13,050,665
Residential mortgage loans held for sale	192,295	[1]	252,316	[2]
Mortgage servicing rights	163,198	[3]	101,172	[4]
Derivative contracts, net of cash margin, Assets, Fair Value	1,097,297	[5]	810,688	[6]
Liabilities [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	275,625	[5]	405,779	[6]
Fair Value, Recurring [Member] | U.S. government securities [Member]
Assets [Abstract]
Trading securities	23,610		9,183
Fair Value, Recurring [Member] | Residential agency mortgage-backed securities [Member]
Assets [Abstract]
Trading securities	9,068,900		4,669,148
Available for sale securities	8,006,616		9,340,471
Fair value option securities	43,770		114,982
Fair Value, Recurring [Member] | Municipal securities [Member]
Assets [Abstract]
Trading securities	25,783		19,172
Available for sale securities	508,365		167,979
Fair Value, Recurring [Member] | U.S. Treasury [Member]
Assets [Abstract]
Available for sale securities	1,000		508
Fair Value, Recurring [Member] | Residential non-agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	24,339		32,770
Fair Value, Recurring [Member] | Commercial agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	4,617,025		3,508,465
Fair Value, Recurring [Member] | Other debt securities [Member]
Assets [Abstract]
Available for sale securities	472		472
Fair Value, Recurring [Member] | Other trading securities [Member]
Assets [Abstract]
Trading securities	18,520		10,472
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets [Abstract]
Trading securities	4,999		4,999
Available for sale securities	1,000		508
Residential mortgage loans held for sale	0	[1]	0	[2]
Mortgage servicing rights	0	[3]	0	[4]
Derivative contracts, net of cash margin, Assets, Fair Value	8,331	[5]	10,780	[6]
Liabilities [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	0	[5]	0	[6]
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. government securities [Member]
Assets [Abstract]
Trading securities	4,999		4,999
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] | U.S. Treasury [Member]
Assets [Abstract]
Available for sale securities	1,000		508
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 1 [Member] | Other trading securities [Member]
Assets [Abstract]
Trading securities	0		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets [Abstract]
Trading securities	9,131,814		4,702,976
Available for sale securities	13,156,345		13,049,685
Residential mortgage loans held for sale	185,969	[1]	245,299	[2]
Mortgage servicing rights	0	[3]	0	[4]
Derivative contracts, net of cash margin, Assets, Fair Value	1,088,966	[5]	799,908	[6]
Liabilities [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	275,625	[5]	405,779	[6]
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. government securities [Member]
Assets [Abstract]
Trading securities	18,611		4,184
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Residential agency mortgage-backed securities [Member]
Assets [Abstract]
Trading securities	9,068,900		4,669,148
Available for sale securities	8,006,616		9,340,471
Fair value option securities	43,770		114,982
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal securities [Member]
Assets [Abstract]
Trading securities	25,783		19,172
Available for sale securities	508,365		167,979
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	24,339		32,770
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	4,617,025		3,508,465
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 2 [Member] | Other trading securities [Member]
Assets [Abstract]
Trading securities	18,520		10,472
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets [Abstract]
Trading securities	0		0
Available for sale securities	472		472
Residential mortgage loans held for sale	6,326	[1]	7,017	[2]
Mortgage servicing rights	163,198	[3]	101,172	[4]
Derivative contracts, net of cash margin, Assets, Fair Value	$ 0	[5]	$ 0	[6]
Liquidity Discount on Mortgage Loans Qualifying for Sale to US Govt Agencies	95.07%		94.57%
Liabilities [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	$ 0	[5]	$ 0	[6]
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		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	472		472
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other trading securities [Member]
Assets [Abstract]
Trading securities	$ 0		$ 0

[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 95.07% 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 94.57% 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 7, Mortgage Banking Activities.

[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 7, Mortgage Banking Activities.

[5] See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in asset positions that were valued based on quoted prices in active markets for identical instruments (Level 1) are primarily exchange-traded interest rate derivative contracts. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded energy derivative contracts, fully offset by cash margin.

[6] See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate derivative contracts, net of cash margin. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate, energy and agricultural contracts, fully offset by cash margin.