CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current Assets:
Allowance for doubtful accounts on trade accounts receivable	$ 56,625	$ 72,278
Common stock par value (in dollars per share)	$ 86.08
Class A common stock
Current Assets:
Common stock par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	1,600,000,000	1,600,000,000
Common stock, shares issued	288,891,958	287,720,957
Common stock, shares outstanding	288,891,958	287,720,957
Class B common stock
Current Assets:
Common stock par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	238,435,208	238,435,208
Common stock, shares outstanding	238,435,208	238,435,208