Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Noncontrolling Interests' Equity [Member]
Beginning Balance at Dec. 31, 2012	$ 480,880	$ 1,548	$ 25,142	$ 125,003	$ (54,930)	$ (38,250)	$ 420,472	$ 1,895
Issuance of common stock under stock option plan	4,069		227	3,842
Purchase of common stock	(3,425)				(3,425)
Redemption of preferred stock	(21)	(21)
Conversion of preferred stock to common stock		$ (1,527)	140	1,387
Stock-based and deferred compensation	2,162		55	2,021	86
Net Income	72,337						72,828	(491)
Other comprehensive income	8,773					8,722		51
Cash dividends paid:
Preferred stock	(43)						(43)
Common stock	(14,431)						(14,431)
Non-qualified stock option and stock award income tax benefit	3,440			3,440
Ending Balance at Dec. 31, 2013	553,741		25,564	135,693	(58,269)	(29,528)	478,826	1,455
Issuance of common stock under stock option plan	1,754		67	1,687
Purchase of common stock	(7,924)				(7,924)
Stock-based and deferred compensation	1,493		9	1,553	(69)
Net Income	57,081						57,101	(20)
Other comprehensive income	(54,454)					(54,417)		(37)
Cash dividends paid:
Common stock	(15,387)						(15,387)
Non-qualified stock option and stock award income tax benefit	640			640
Ending Balance at Dec. 31, 2014	536,944		25,640	139,573	(66,262)	(83,945)	520,540	1,398
Issuance of common stock under stock option plan	777		45	732
Purchase of common stock	(2,000)				(2,000)
Stock-based and deferred compensation	3,694		24	3,854	(184)
Net Income	76,037						75,968	69
Other comprehensive income	(41,210)					(41,143)		(67)
Cash dividends paid:
Common stock	(16,300)						(16,300)
Non-qualified stock option and stock award income tax benefit	442			442
Ending Balance at Dec. 31, 2015	$ 558,384		$ 25,709	$ 144,601	$ (68,446)	$ (125,088)	$ 580,208	$ 1,400