Accounts Receivable Sales Agreement (Details) - USD ($) $ in Thousands	Jul. 13, 2021	Sep. 30, 2021	Jul. 12, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Accounts Receivable Sales Agreement
Cash and cash equivalents		$ 771,878		$ 472,246	$ 504,985	$ 435,990
5.50% senior notes due January 2023
Accounts Receivable Sales Agreement
Interest rate (as a percent)		5.50%
Accounts Receivable Sales Agreement
Accounts Receivable Sales Agreement
Agreement amount	$ 150,000		$ 250,000
Agreement expiration term extension (in years)	2 years
Accounts receivables sold to purchasers		$ 96,000		54,000
Trade receivables pledged as collateral		$ 41,800		$ 63,100