Stockholders' Equity and Restrictions Change in Common Shares (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Treasury Stock [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued	(3,136,000)	(3,136,000)	(3,136,000)	(3,136,000)
Stock Issued During Period, Shares, Period Increase (Decrease)	0	0	0
Common Stock Class A [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued	52,364,993	52,215,852	52,216,000	52,216,000
Stock Issued During Period, Shares, Period Increase (Decrease)	149,000	0	0
Common Stock Class B [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued	1,001,714	1,001,714	1,002,000	1,002,000
Stock Issued During Period, Shares, Period Increase (Decrease)	0	0	0