CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (16,973)	$ (4,163)	$ 50,699	$ (9,979)
Other comprehensive income (loss):
Change in foreign currency translation adjustment (net of income tax expense (recovery) of nil and $48 for the three and six months ended June 30, 2013; 2012-$1 and ($5))	(1,114)	(112)	(1,937)	(47)
Foreign currency translation reclassified from accumulated other comprehensive income (note 3)			1,865
Other comprehensive loss	(1,114)	(112)	(72)	(47)
Comprehensive income (loss)	$ (18,087)	$ (4,275)	$ 50,627	$ (10,026)