Consolidated Balance Sheets Parenthetical - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 5,879	$ 7,073
Common stock stated value per share (USD per share)	$ 20	$ 20
Authorized	50,000,000	50,000,000
Issued to voting trustees	13,668,055	13,159,559
Issued to shareholders	2,721,926	2,714,853
In treasury, at cost	(65,890)	(14,482)
Outstanding Common Stock	16,324,091	15,859,930
Common Stock, Shares Subscribed	878,608	806,811
Subscripton Receivable	(878,608)	(806,811)