Condensed Consolidated Balance Sheets Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 6,453	$ 7,073
Common, stated value per share	$ 20	$ 20
Authorized	50,000,000	50,000,000
Issued to voting trustees	13,760,828	13,159,559
Issued to shareholders	2,771,108	2,714,853
In treasury, at cost	(547,260)	(14,482)
Outstanding common stock	15,984,676	15,859,930