Loans and Allowance for Credit Losses on Loans - Age Analysis (Details) - USD ($)	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	$ 19,844,237,000		$ 22,871,961,000
Non-accrual	35,864,000
Non-Accrual With No Allowance	3,637,000
Nonaccrual, interest income	801,000	$ 1,800,000
Interest income reversed	100,000
30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	11,157,000
60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	2,604,000
Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	30,664,000
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	44,425,000
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	19,763,948,000
Commercial
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	8,813,614,000		9,897,561,000
Non-accrual	27,968,000
Non-Accrual With No Allowance	3,637,000
Commercial | 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	10,405,000
Commercial | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	151,000
Commercial | Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	30,602,000
Commercial | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	41,158,000
Commercial | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	8,744,488,000
Energy
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	1,106,097,000		721,373,000
Non-accrual	6,500,000
Non-Accrual With No Allowance	0
Energy | 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Energy | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Energy | Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Energy | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Energy | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	1,099,597,000
Mortgage finance
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	4,908,822,000		7,475,497,000
Non-accrual	0
Non-Accrual With No Allowance	0
Mortgage finance | 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Mortgage finance | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Mortgage finance | Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Mortgage finance | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Mortgage finance | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	4,908,822,000
Real estate
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	5,015,704,000		$ 4,777,530,000
Real estate | Commercial Real Estate
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	3,310,272,000
Non-accrual	187,000
Non-Accrual With No Allowance	0
Real estate | Residential Homebuilder Finance
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	600,567,000
Non-accrual	0
Non-Accrual With No Allowance	0
Real estate | Other Financing Receivable
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	790,267,000
Non-accrual	1,081,000
Non-Accrual With No Allowance	0
Real estate | Secured by 1-4 family
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	314,598,000
Non-accrual	128,000
Non-Accrual With No Allowance	0
Real estate | 30 to 59 Days Past Due | Commercial Real Estate
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	52,000
Real estate | 30 to 59 Days Past Due | Residential Homebuilder Finance
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Real estate | 30 to 59 Days Past Due | Other Financing Receivable
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	700,000
Real estate | 30 to 59 Days Past Due | Secured by 1-4 family
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Real estate | 60 to 89 Days Past Due | Commercial Real Estate
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Real estate | 60 to 89 Days Past Due | Residential Homebuilder Finance
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Real estate | 60 to 89 Days Past Due | Other Financing Receivable
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	2,453,000
Real estate | 60 to 89 Days Past Due | Secured by 1-4 family
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Real estate | Greater Than 90 Days | Commercial Real Estate
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Real estate | Greater Than 90 Days | Residential Homebuilder Finance
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Real estate | Greater Than 90 Days | Other Financing Receivable
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Real estate | Greater Than 90 Days | Secured by 1-4 family
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	62,000
Real estate | Financial Asset, Past Due | Commercial Real Estate
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	52,000
Real estate | Financial Asset, Past Due | Residential Homebuilder Finance
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	0
Real estate | Financial Asset, Past Due | Other Financing Receivable
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	3,153,000
Real estate | Financial Asset, Past Due | Secured by 1-4 family
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	62,000
Real estate | Financial Asset, Not Past Due | Commercial Real Estate
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	3,310,033,000
Real estate | Financial Asset, Not Past Due | Residential Homebuilder Finance
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	600,567,000
Real estate | Financial Asset, Not Past Due | Other Financing Receivable
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	786,033,000
Real estate | Financial Asset, Not Past Due | Secured by 1-4 family
Financing Receivable, Past Due [Line Items]
Financing receivable, excluding accrued interest, before allowance for credit loss	$ 314,408,000