Stockholders' Equity and Restrictions Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss) Attributable to Parent	$ 1,538	$ (7,915)	$ (1,027)	$ (3,584)	$ 4,951	$ 2,046	$ (4,565)	$ (3,802)	$ (10,988)	$ (1,370)	$ (11,062)
Weighted Average Number of Shares Outstanding, Basic									50,402	50,216	50,082
Weighted Average Number of Shares Outstanding, Diluted									50,940	50,349	50,141
Common Stock Class A [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic									$ (10,878)	$ (1,356)	$ (10,950)
Net Income (Loss) Available to Common Stockholders, Diluted									$ (10,878)	$ (1,356)	$ (10,950)
Weighted Average Number of Shares Outstanding, Basic									49,400	49,214	49,080
Weighted Average Number of Shares Outstanding, Diluted									49,938	49,347	49,139
Basic and diluted earnings (losses) per share common stock	$ 0.03	$ (0.16)	$ (0.02)	$ (0.07)	$ 0.10	$ 0.04	$ (0.09)	$ (0.08)	$ (0.22)	$ (0.03)	$ (0.22)
Common Stock Class B [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic									$ (110)	$ (14)	$ (112)
Net Income (Loss) Available to Common Stockholders, Diluted									$ (110)	$ (14)	$ (112)
Weighted Average Number of Shares Outstanding, Basic and Diluted									1,002	1,002	1,002
Basic and diluted earnings (losses) per share common stock	$ 0.01	$ (0.07)	$ (0.01)	$ (0.04)	$ 0.05	$ 0.02	$ (0.04)	$ (0.04)	$ (0.11)	$ (0.01)	$ (0.11)