Condensed Consolidated Statements of Changes in Equity - 6 months ended Jun. 30, 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]	Performance Share Units [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			69,116		236		69,352
Other comprehensive income (loss)				7,232	(2)		7,230
Comprehensive income			69,116	7,232	234		76,582
Change in value of redeemable NCI			(20,249)				(20,249)
Stock option exercises	$ 22,750	(4,693)					18,057
Stock option exercises, shares	806,569
Stock option tax adjustment		186					186
Stock option compensation expense (note 21)		2,470					2,470
Modification of PSUs (note 21)			(70)			$ 2,175	(70)
NCI acquired in a business combination (note 23)					596		596
Acquisition of NCI (note 23)					(226)		(226)
Shares repurchased (note 20)	$ (36,726)						(36,726)
Shares repurchased, shares	(1,460,000)
Cash dividends paid (note 20)			(34,176)		(72)		(34,248)
Balance at Jun. 30, 2016	$ 117,554	$ 25,691	$ 615,672	$ (49,901)	$ 4,715		713,731
Balance, shares at Jun. 30, 2016	106,547,039
Contingently redeemable non-controlling interest, Balance at Dec. 31, 2015							24,785
Net income							1,233
Other comprehensive income (loss)							170
Comprehensive Income attributable redeemable non-controlling interests							1,403
Change in value of contingently redeemable NCI							20,249
Cash dividends paid (note 20)							(2,296)
Contingently redeemable non-controlling interest, Balance at Jun. 30, 2016							44,141
Equity-classified PSU expense (note 21)						486
Contingently redeemable Performance share units, Balance at Jun. 30, 2016						$ 2,661	$ 2,661