Fair Value Measurements - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held-for-sale	$ 107,417	$ 221,784
Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	8,403,788	8,284,723
Loans held-for-sale	107,417	221,784
Recurring \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	0	0
Loans held-for-sale	0	0
Recurring \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	8,403,321	8,284,219
Loans held-for-sale	107,417	221,784
Recurring \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	467	504
Loans held-for-sale	0	0
Carrying Amount \| Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held-for-sale	232	244
Net loans	32,806,406	31,164,287
Securitization receivable	19,992	19,949
Deferred fees on commitments to extend credit	18,477	20,002
Total financial instrument assets	33,413,299	31,709,277
Certificates of deposits	4,665,211	5,524,381
Long-term borrowings	1,518,816	1,374,732
Total financial instrument liabilities	6,184,027	6,899,113
Carrying Amount \| Recurring \| FHLB and FRB stocks
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	358,414	320,436
Carrying Amount \| Recurring \| Investment securities held-to-maturity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	209,778	184,359
Estimated Fair Value \| Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held-for-sale	233	248
Net loans	32,983,379	31,434,749
Securitization receivable	19,992	19,916
Deferred fees on commitments to extend credit	18,477	20,002
Total financial instrument assets	33,592,906	31,988,905
Certificates of deposits	4,670,257	5,534,751
Long-term borrowings	1,562,225	1,416,355
Total financial instrument liabilities	6,232,482	6,951,106
Estimated Fair Value \| Recurring \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held-for-sale	0	0
Net loans	0	0
Securitization receivable	0	0
Deferred fees on commitments to extend credit	0	0
Total financial instrument assets	0	0
Certificates of deposits	0	0
Long-term borrowings	0	0
Total financial instrument liabilities	0	0
Estimated Fair Value \| Recurring \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held-for-sale	0	0
Net loans	0	0
Securitization receivable	0	0
Deferred fees on commitments to extend credit	18,477	20,002
Total financial instrument assets	585,675	530,579
Certificates of deposits	4,670,257	5,534,751
Long-term borrowings	1,562,225	1,416,355
Total financial instrument liabilities	6,232,482	6,951,106
Estimated Fair Value \| Recurring \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held-for-sale	233	248
Net loans	32,983,379	31,434,749
Securitization receivable	19,992	19,916
Deferred fees on commitments to extend credit	0	0
Total financial instrument assets	33,007,231	31,458,326
Certificates of deposits	0	0
Long-term borrowings	0	0
Total financial instrument liabilities	0	0
Estimated Fair Value \| Recurring \| FHLB and FRB stocks
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	358,414	320,436
Estimated Fair Value \| Recurring \| FHLB and FRB stocks \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	0	0
Estimated Fair Value \| Recurring \| FHLB and FRB stocks \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	358,414	320,436
Estimated Fair Value \| Recurring \| FHLB and FRB stocks \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	0	0
Estimated Fair Value \| Recurring \| Investment securities held-to-maturity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	212,411	193,554
Estimated Fair Value \| Recurring \| Investment securities held-to-maturity \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	0	0
Estimated Fair Value \| Recurring \| Investment securities held-to-maturity \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	208,784	190,141
Estimated Fair Value \| Recurring \| Investment securities held-to-maturity \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available-for-sale	$ 3,627	$ 3,413

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- Definition

Represents the fair value of various categories of unpaid commercial loans and other financial instruments.

+ References

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- Definition

Loans And Leases Receivable, Net, Fair Value Disclosure

+ References

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- Definition

Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

+ References

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

+ References

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

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