Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets:
Accounts receivable, allowances	$ 4,182	$ 4,962
Property and equipment
Accumulated depreciation	$ 321,999	$ 305,575
Equity:
Common stock, shares authorized	775,000,000
Common Class A [Member]
Equity:
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	77,037,205	79,113,916
Common stock, shares outstanding	77,037,205	79,113,916
Common Class B [Member]
Equity:
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	275,000,000	275,000,000
Common stock, shares issued	22,430,097	22,430,097
Common stock, shares outstanding	22,430,097	22,430,097