Loans and Allowance for Credit Losses on Loans - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 211,866	$ 254,615
Provision for credit losses on loans	19,284	(24,313)
Charge-offs	3,328	11,473
Recoveries	1,191	2,682
Net charge-offs (recoveries)	2,137	8,791
Ending balance	229,013	221,511
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	102,202	73,061
Provision for credit losses on loans	16,343	12,035
Charge-offs	2,978	3,863
Recoveries	436	1,358
Net charge-offs (recoveries)	2,542	2,505
Ending balance	116,003	82,591
Energy
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	52,568	84,064
Provision for credit losses on loans	(26,500)	(23,768)
Charge-offs	0	6,418
Recoveries	755	1,324
Net charge-offs (recoveries)	(755)	5,094
Ending balance	26,823	55,202
Mortgage finance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	6,083	4,699
Provision for credit losses on loans	12,975	352
Charge-offs	0	0
Recoveries	0	0
Net charge-offs (recoveries)	0	0
Ending balance	19,058	5,051
Real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	51,013	92,791
Provision for credit losses on loans	16,466	(12,932)
Charge-offs	350	1,192
Recoveries	0	0
Net charge-offs (recoveries)	350	1,192
Ending balance	$ 67,129	$ 78,667

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

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- Definition

Amount, excluding accrued interest, of increase (decrease) in allowance for credit loss on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

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- Definition

Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (e)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

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- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

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- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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-Section S99
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-URI https://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

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