Reserves for Credit Losses (Details)	Sep. 30, 2021	Dec. 31, 2020
U.S. Unemployment Rate | Third quarter of 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.05
U.S. Unemployment Rate | Minimum | Third quarter of 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input		0.07
U.S. Unemployment Rate | Minimum | Fourth quarter of 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.05	0.07
U.S. Unemployment Rate | Minimum | Fourth quarter of 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.04	0.06
U.S. Unemployment Rate | Minimum | Fourth quarter of 2023
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.03	0.04
U.S. Unemployment Rate | Maximum | Third quarter of 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input		0.11
U.S. Unemployment Rate | Maximum | Fourth quarter of 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.07	0.11
U.S. Unemployment Rate | Maximum | Fourth quarter of 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.09	0.12
U.S. Unemployment Rate | Maximum | Fourth quarter of 2023
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.07	0.10
U.S. GDP Growth (Contraction) | Third quarter of 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.08
U.S. GDP Growth (Contraction) | Minimum | Third quarter of 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input		0.03
U.S. GDP Growth (Contraction) | Minimum | Fourth quarter of 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.06	0.06
U.S. GDP Growth (Contraction) | Minimum | Fourth quarter of 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.02	0.04
U.S. GDP Growth (Contraction) | Minimum | Fourth quarter of 2023
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.04	0.05
U.S. GDP Growth (Contraction) | Maximum | Third quarter of 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input		(0.03)
U.S. GDP Growth (Contraction) | Maximum | Fourth quarter of 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	(0.04)	(0.02)
U.S. GDP Growth (Contraction) | Maximum | Fourth quarter of 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.01	0.03
U.S. GDP Growth (Contraction) | Maximum | Fourth quarter of 2023
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, reserves for credit losses, measurement input	0.03	0.03