Stockholders Equity Recon of Outstanding Common Stock table & Text (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Shares of common stock repurchased			(66,475)	(129,011)
Purchase of common stock		$ (2,043)	$ (4,577)	$ (8,849)
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 36,300		$ 36,300
Common Stock, Shares, Outstanding	24,659,885	24,818,209	24,659,885	24,818,209	24,718,815	24,930,526
Stock Issued During Period, Shares, Stock-based Compensation, Net of Forfeitures			7,545	16,694
Stock-based compensation	$ 10	$ 102	$ 212	$ 320
Common Class A
Class of Stock [Line Items]
Shares of common stock repurchased			(66,475)	(129,011)
Common Stock, Shares, Outstanding	24,648,472	24,806,796	24,648,472	24,806,796	24,707,402	24,919,113
Common stock, without par value	$ 152,454		$ 152,454		$ 152,652
Stock Issued During Period, Shares, Stock-based Compensation, Net of Forfeitures			7,545	16,694
Common Class B
Class of Stock [Line Items]
Shares of common stock repurchased			0	0
Common Stock, Shares, Outstanding	11,413	11,413	11,413	11,413	11,413	11,413
Common stock, without par value	$ 72		$ 72		$ 72
Stock Issued During Period, Shares, Stock-based Compensation, Net of Forfeitures			0	0
Common Stock
Class of Stock [Line Items]
Purchase of common stock		$ (183)	$ (410)	$ (795)
Common stock, without par value	152,526	153,186	152,526	153,186	152,724	$ 153,661
Stock-based compensation	10	102	212	320
Common Stock | Common Class A
Class of Stock [Line Items]
Purchase of common stock			(410)	(795)
Common stock, without par value	152,454	153,114	152,454	153,114	152,652	153,589
Stock-based compensation			212	320
Common Stock | Common Class B
Class of Stock [Line Items]
Purchase of common stock			0	0
Common stock, without par value	$ 72	$ 72	72	72	$ 72	$ 72
Stock-based compensation			$ 0	$ 0