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, 2012	$ 611,445	$ 96	$ 181,627	$ (12,559)	$ (45,379)	$ 470,628	$ 17,032
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	43,044					42,117	927
Other comprehensive income	3,354				3,354
Noncontrolling Interest, cash distributions or proceeds received	152						152
Stock awards, stock option exercises and other shares issued to employees and directors, net of income tax of $1,522 (215 shares) and $1,099 (128 shares) for the period June 30, 2014 and 2013, respectively	1,884		773	1,111
Dividends declared ($0.2200 and $0.2133 per common share for the year June 30, 2014 and 2013, respectively)	(5,999)					(5,999)
Performance share unit dividend equivalents	0		55			(55)
Ending Balance at Jun. 30, 2013	653,880	96	182,455	(11,448)	(42,025)	506,691	18,111
Beginning Balance at Dec. 31, 2013	724,421	96	184,380	(10,222)	(21,181)	548,401	22,947
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	75,399					67,009	8,390
Other comprehensive income	(5,842)				(5,842)
Noncontrolling Interest, cash distributions or proceeds received	(2,451)						(2,451)
Stock awards, stock option exercises and other shares issued to employees and directors, net of income tax of $1,522 (215 shares) and $1,099 (128 shares) for the period June 30, 2014 and 2013, respectively	6,063		4,642	1,421
Payment of cash in lieu for stock split (187 shares)	(58)		(58)
Dividends declared ($0.2200 and $0.2133 per common share for the year June 30, 2014 and 2013, respectively)	(6,252)					(6,252)
Performance share unit dividend equivalents	0		134			(134)
Ending Balance at Jun. 30, 2014	$ 791,280	$ 96	$ 189,098	$ (8,801)	$ (27,023)	$ 609,024	$ 28,886