Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Activity in Allowance for Unfunded Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	$ 304,924	$ 280,903	$ 255,024
Provision for (Reduction of) Loans	189,226	94,183	84,292
Foreign Currency Translation Adjustments	2,037	1,403	(2,132)
Allowance for credit loss, ending balance	447,765	304,924	280,903
Cumulative adjustment for adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	25,464
Allowance for credit loss, ending balance		25,464
Unfunded credit commitments
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	67,656	55,183	51,770
Provision for (Reduction of) Loans	30,066	12,233	3,578
Foreign Currency Translation Adjustments	248	240	(165)
Allowance for credit loss, ending balance	120,796	67,656	55,183
Unfunded credit commitments \| Cumulative adjustment for adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	$ 22,826	0	0
Allowance for credit loss, ending balance		$ 22,826	$ 0

Amount of gain (loss) from converting allowance reserve for credit loss to currency of reporting entity from amount denominated or measured in a different currency, which decreases (increases) the allowance for loan and lease losses.

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of credit loss expense (reversal of expense) for financing receivable.

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