Investment Securities, Gains, Losses, and Proceeds (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Gross gains on AFS securities		$ 421	$ 9,312	$ 6,374
Gross (losses) on AFS securities		(437)	(90)	(13,861)
Carrying value changes		0	0	13,444
Investment securities gains (losses), net		(16)	9,222	5,957
Proceeds from sales of investment securities	$ 51,000	$ 158,708	$ 626,283	$ 1,367,476

Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27357-111563

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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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Amount of gain from upward price adjustment on investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123583765&loc=SL75117539-209714

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The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period.

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