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Debt - Senior Unsecured Notes (Details) - USD ($)					3 Months Ended
Debt - Senior Unsecured Notes (Details) - USD ($)	May 04, 2021	Feb. 26, 2021	Jul. 09, 2020	Jun. 24, 2020	Mar. 31, 2021	Mar. 31, 2020	Jan. 28, 2021	Dec. 31, 2020	Jun. 23, 2020
Debt Instrument
Principal balance on debt					$ 5,803,487,000
Senior unsecured note issuances					4,255,697,000			$ 5,697,586,000
Loss on extinguishment of debt					164,292,000	$ (833,000)
Senior Unsecured Note
Debt Instrument
Principal balance on debt					4,300,000,000
Senior unsecured note issuances					$ 0
Senior Unsecured Note \| Subsequent Event
Debt Instrument
Repayments of unsecured debt	$ 550,000,000
Senior Unsecured Note \| Unsecured Note 4.250 Percent
Debt Instrument
Amount		$ 188,000,000		$ 250,000,000			$ 112,000,000
Coupon Rate		4.25%		4.25%			4.25%
Loss on extinguishment of debt				$ 26,000,000
Senior Unsecured Note \| Unsecured Note 4.200 Percent
Debt Instrument
Amount		$ 149,000,000					$ 201,000,000
Coupon Rate		4.20%					4.20%
Senior Unsecured Note \| Unsecured Note 3.880 Percent
Debt Instrument
Amount		$ 331,000,000					$ 469,000,000
Coupon Rate		3.88%					3.88%
Senior Unsecured Note \| Senior Notes Due 2023 and 2024
Debt Instrument
Loss on extinguishment of debt		$ 164,000,000
Senior Unsecured Note \| 2031 Notes
Debt Instrument
Amount									$ 600,000,000
Coupon Rate									2.88%
Senior Unsecured Note \| Unsecured note 3.150 percent
Debt Instrument
Amount			$ 300,000,000
Coupon Rate			3.15%
Loss on extinguishment of debt			$ 18,000,000
Senior Unsecured Note \| Unsecured Note 3.40 Percent \| Subsequent Event
Debt Instrument
Coupon Rate	3.40%
Repayments of unsecured debt	$ 250,000,000
Senior Unsecured Note \| Unsecured Note 4.00 Percent \| Subsequent Event
Debt Instrument
Coupon Rate	4.00%
Repayments of unsecured debt	$ 300,000,000