CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Allowance for accounts receivable	$ 24,699	$ 18,860
Accumulated depreciation and amortization of property and equipment	298,113	286,798
Accumulated amortization of intangible assets	$ 175,570	$ 136,405
Treasury stock (shares)	194,708,000	194,708,000
Common stock $.001 par value; authorized 1,600,000 shares; issued 262,789 and 262,303 shares, respectively, and outstanding 78,449 and 77,963 shares, respectively
Par value of common stock (USD per share)	$ 0.001	$ 0.001
Common stock authorized (shares)	1,600,000,000	1,600,000,000
Common stock issued (shares)	262,789,000	262,303,000
Common stock outstanding (shares)	78,449,000	77,963,000
Class B convertible common stock $.001 par value; authorized 400,000 shares; issued 16,157 shares and outstanding 5,789 shares
Par value of common stock (USD per share)	$ 0.001	$ 0.001
Common stock authorized (shares)	400,000,000	400,000,000
Common stock issued (shares)	16,157,000	16,157,000
Common stock outstanding (shares)	5,789,000	5,789,000