Condensed Consolidated Statements of Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total		Common Shares	Additional Paid-in Capital	Treasury Shares	Accumulated Other Comprehensive Loss	Retained Earnings	Noncontrolling Interests
Beginning Balance at Dec. 31, 2011	$ 538,842		$ 96	$ 179,463	$ (14,997)	$ (43,090)	$ 402,523	$ 14,847
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	61,390						64,490	(3,100)
Other comprehensive income	483					483
Proceeds received from minority investor	6,100							6,100
Stock awards, stock option exercises and other shares issued to employees and directors, net of income tax of $1,201 (98 shares) and $678 (139 shares) for the period September 30, 2013 and 2012, respectively	3,991			1,535	2,456
Dividends declared ($0.48 and $0.45 per common share for the year September 30, 2013 and 2012, respectively)	(8,386)						(8,386)
Ending Balance at Sep. 30, 2012	602,420		96	180,998	(12,541)	(42,607)	458,627	17,847
Beginning Balance at Dec. 31, 2012	611,445		96	181,627	(12,559)	(45,379)	470,628	17,032
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	61,083						59,278	1,805
Other comprehensive income	3,793	[1]				3,793
Proceeds received from minority investor	151							151
Stock awards, stock option exercises and other shares issued to employees and directors, net of income tax of $1,201 (98 shares) and $678 (139 shares) for the period September 30, 2013 and 2012, respectively	2,823			1,591	1,232
Dividends declared ($0.48 and $0.45 per common share for the year September 30, 2013 and 2012, respectively)	(9,003)						(9,003)
Performance share unit dividend equivalents	0			55			(55)
Ending Balance at Sep. 30, 2013	$ 670,292		$ 96	$ 183,273	$ (11,327)	$ (41,586)	$ 520,848	$ 18,988

[1] All amounts are net of tax. Amounts in parentheses indicates debits