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Notes Payable - Note Repayment Narrative (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Debt
Loss on extinguishment of debt			$ 3,983	$ 0	$ 50,456	$ 9,819
Notes payable \| 3.250% notes, $450 issued in October 2012 and $500 issued in December 2017, both due in October 2022
Debt
Early redemption of notes payable	$ 950,000
Interest rate (as a percent)	3.25%						3.25%
Loss on extinguishment of debt					$ 46,500
Notes payable \| 5.750% notes, issued in June 2010 and due in January 2021
Debt
Early redemption of notes payable		$ 250,000
Interest rate (as a percent)		5.75%
Loss on extinguishment of debt						$ 9,800