Condensed Consolidated Balance Sheets Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 6,705	$ 7,073
Common, stated value per share	$ 20	$ 20
Authorized	50,000,000	50,000,000
Issued to voting trustees	13,622,354	13,159,559
Issued to shareholders	2,757,313	2,714,853
In treasury, at cost	(413,179)	(14,482)
Outstanding common stock	15,966,488	15,859,930