Condensed Consolidated Statements of Changes in Equity - 3 months ended Mar. 31, 2016 - 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, 2015	$ 131,530	$ 27,728	$ 601,051	$ (57,133)	$ 4,183	$ 707,359
Balance, shares at Dec. 31, 2015	107,200,470
Net income			29,406		117	29,523
Other comprehensive income				12,028		12,028
Comprehensive income			29,406	12,028	117	41,551
Change in value of redeemable non-controlling interest			(18,317)			(18,317)
Stock option exercises	$ 3,809	(778)				3,031
Stock option exercises, shares	145,190
Stock option tax adjustment		(51)				(51)
Stock option compensation expense (note 21)		1,070				1,070
Non-controlling interest acquired in a business combination (note 23)					488	488
Shares repurchased (note 20)	$ (36,726)					(36,726)
Shares repurchased, shares	(1,460,000)
Cash dividends paid (note 20)			(17,154)			(17,154)
Balance at Mar. 31, 2016	$ 98,613	$ 27,969	$ 594,986	$ (45,105)	$ 4,788	681,251
Balance, shares at Mar. 31, 2016	105,885,660
Contingently redeemable non-controlling interest, Balance at Dec. 31, 2015						24,785
Net income						471
Other comprehensive income						167
Comprehensive Income attributable redeemable non-controlling interests						638
Change in value of contingently redeemable non-controlling interest						18,317
Cash dividends paid (note 20)						(2,296)
Contingently redeemable non-controlling interest, Balance at Mar. 31, 2016						$ 41,444