CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accounts receivable allowance	$ 17,953	$ 16,603
Property and equipment accumulated depreciation and amortization	41,397	36,473
Accumulated amortization of intangible assets	$ 100,358	$ 85,589
Class A common stock, $0.001 par value; authorized 2,000,000 shares; 84,718 and 80,515 shares issued and outstanding
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock authorized (shares)	2,000,000,000	2,000,000,000
Common stock issued (shares)	84,718,000	80,515,000
Common stock outstanding (shares)	84,718,000	80,515,000
Class B convertible common stock, $0.001 par value; authorized 1,500,000 shares; 421,452 and 421,118 shares issued and outstanding
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock authorized (shares)	1,500,000,000	1,500,000,000
Common stock issued (shares)	421,452,000	421,118,000
Common stock outstanding (shares)	421,452,000	421,118,000
Class C common stock, $0.001 par value; authorized 1,500,000 shares; no shares issued and outstanding
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock authorized (shares)	1,500,000,000	1,500,000,000
Common stock issued (shares)	0	0
Common stock outstanding (shares)	0	0