Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Common stock [Member]	Additional paid-In capital [Member]	Retained earnings [Member]	Accumulated other comprehensive income (loss) [Member]	Non-controlling interest [Member]	Total
Balance at Dec. 31, 2012	$ 118,694	$ 27,169	$ 474,843	$ 32,378		$ 653,084
Balance, shares at Dec. 31, 2012	106,596,811
Net income			93,644			93,644
Change in value of redeemable non-controlling interest			(3,998)			(3,998)
Other comprehensive loss				(13,442)		(13,442)
Comprehensive income			89,646	(13,442)		76,204
Stock option exercises	$ 7,656	(1,504)				6,152
Stock option exercises, shares	427,972
Stock option tax adjustment		69				69
Stock option compensation expense (note 25)		4,504				4,504
Cash dividends paid (note 24)			(53,918)			(53,918)
Balance at Dec. 31, 2013	$ 126,350	30,238	510,571	18,936		686,095
Balance, shares at Dec. 31, 2013	107,024,783
Contingently redeemable non-controlling interest, Balance at Dec. 31, 2012						3,504
Net income						801
Change in value of contingently redeemable non-controlling interest						3,998
Comprehensive Income attributable redeemable non-controlling interests						4,799
Contingently redeemable non-controlling interest, Balance at Dec. 31, 2013						8,303
Net income			90,981			90,981
Change in value of redeemable non-controlling interest			(7,512)			(7,512)
Other comprehensive loss				(35,686)		(35,686)
Comprehensive income			83,469	(35,686)		47,783
Stock option exercises	$ 14,907	(2,786)				12,121
Stock option exercises, shares	663,152
Stock option tax adjustment		152				152
Stock option compensation expense (note 25)		3,710				3,710
Cash dividends paid (note 24)			(57,929)			(57,929)
Balance at Dec. 31, 2014	$ 141,257	31,314	536,111	(16,750)		691,932
Balance, shares at Dec. 31, 2014	107,687,935
Net income						1,582
Change in value of contingently redeemable non-controlling interest						7,512
Other comprehensive income (loss)						(110)
Comprehensive Income attributable redeemable non-controlling interests						8,984
Contingently redeemable non-controlling interest, Balance at Dec. 31, 2014						17,287
Net income			136,214		$ 64	136,278
Change in value of redeemable non-controlling interest			(6,934)			(6,934)
Other comprehensive loss				(40,383)		(40,383)
Comprehensive income			129,280	(40,383)	64	88,961
Stock option exercises	$ 37,762	(7,946)				29,816
Stock option exercises, shares	1,412,535
Stock option tax adjustment		359				359
Stock option compensation expense (note 25)		4,001				4,001
Non-controlling interest acquired in a business combination (note29)					4,119	4,119
Shares repurchased (note 24)	$ (47,489)					(47,489)
Shares repurchased, shares	(1,900,000)
Cash dividends paid (note 24)			(64,340)			(64,340)
Balance at Dec. 31, 2015	$ 131,530	$ 27,728	$ 601,051	$ (57,133)	$ 4,183	707,359
Balance, shares at Dec. 31, 2015	107,200,470
Net income						2,297
Change in value of contingently redeemable non-controlling interest						6,934
Other comprehensive income (loss)						(393)
Comprehensive Income attributable redeemable non-controlling interests						8,838
Cash dividends paid (note 25)						(1,340)
Contingently redeemable non-controlling interest, Balance at Dec. 31, 2015						$ 24,785