Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Receivables, reserve	$ 14	$ 14
Intangible assets, accumulated amortization	21,663	12,856
Property and equipment, accumulated depreciation	$ 101,752	$ 94,766
Treasury stock, shares (in shares)	10,070,813	8,375,077
Class A
Common stock, no par value (usd per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	20,000	20,000
Common stock, shares issued (in shares)	9,000	9,000
Common stock, shares outstanding (in shares)	9,000	9,000
Class B
Common stock, no par value (usd per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	900,000,000	900,000,000
Common stock, shares issued (in shares)	109,505,456	109,505,456
Common stock, shares outstanding (in shares)	99,434,643	101,130,379