Notes Payable - Callable Medium-Term Notes (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
2023	$ 3,469,814	$ 3,004,203
2024	2,547,497	2,809,551
2025	1,463,668	927,119
Total principal net of discounts	$ 21,683,406	$ 21,795,677
Weighted - average rate (as a percent)	1.15%	1.37%
2022
Debt Instrument [Line Items]
2022	$ 3,187,154
Weighted - average rate (as a percent)	0.90%
2023
Debt Instrument [Line Items]
2023	$ 2,896,525
Weighted - average rate (as a percent)	1.08%
2024
Debt Instrument [Line Items]
2024	$ 1,650,373
Weighted - average rate (as a percent)	1.05%
2025
Debt Instrument [Line Items]
2025	$ 1,483,928
Weighted - average rate (as a percent)	0.94%
Thereafter
Debt Instrument [Line Items]
Thereafter	$ 4,285,890
Weighted - average rate (as a percent)	1.73%
Call Option
Debt Instrument [Line Items]
2022	$ 147,480
2023	245,831
2024	159,393
2025	192,827
Thereafter	845,922
Total principal net of discounts	$ 1,591,453
Weighted - average rate (as a percent)	1.10%
Call Option \| 2022
Debt Instrument [Line Items]
Weighted - average rate (as a percent)	0.12%
Call Option \| 2023
Debt Instrument [Line Items]
Weighted - average rate (as a percent)	0.90%
Call Option \| 2024
Debt Instrument [Line Items]
Weighted - average rate (as a percent)	0.77%
Call Option \| 2025
Debt Instrument [Line Items]
Weighted - average rate (as a percent)	0.75%
Call Option \| Thereafter
Debt Instrument [Line Items]
Weighted - average rate (as a percent)	1.47%

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Weighted average interest rate of long-term debt outstanding calculated at point in time.

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