Contractual interest rate for funds borrowed, under the debt agreement.

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Notes Payable - Note Repayments (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt
Loss on extinguishment of debt				$ (9,819)	$ 0	$ 0
Notes payable \| 5.750% notes, issued in June 2010 and due in January 2021
Debt
Early repayment of notes payable		$ 250,000
Interest rate (as a percent)		5.75%			5.75%
Loss on extinguishment of debt			$ (9,800)
Notes payable \| 3.250% notes due in October 2022
Debt
Interest rate (as a percent)				3.25%
Notes payable \| 3.250% notes due in October 2022 \| Subsequent event
Debt
Early repayment of notes payable	$ 950,000
Interest rate (as a percent)	3.25%