Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accounts receivable, trade, allowance for doubtful accounts	$ 8,610	$ 5,733
Property and equipment, accumulated depreciation	$ 352,655	$ 347,302
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	45,000,000	45,000,000
Preferred stock, shares issued	0	0
Class A Common Stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	360,000,000	360,000,000
Common stock, shares issued	64,347,000	63,886,000
Common stock, shares outstanding	41,244,000	44,078,000
Treasury stock, shares	23,102,000	19,808,000
Class B Common Stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	11,484,000	11,484,000