Capital Stock (Tables)

6 Months Ended

Jun. 30, 2011

Capital Stock [Abstract]

Weighted average fair value of common share granted to employees

	Three Months Ended June 30,						Six Months Ended June 30,
	2011			2010			2011			2010
Average risk-free interest rate		2.34%			3.09%			2.79%			3.11%
Expected option life (in years)		1.78 - 5.14			2.99 - 5.33			1.78 - 5.14			2.99 - 5.39
Expected volatility		50%			61%			50%			61%
Annual termination probability		0% - 8.31	%		0% - 9.69	%		0% - 8.49	%		0% - 9.69	%
Dividend yield		0%			0%			0%			0%

Option activity under the Stock Option Plan

							Weighted Average Exercise
	Number of Shares						Price Per Share
	2011			2010			2011		2010
Options outstanding, beginning of year		6,743,272			6,173,795		$	10.79	$	6.52
Granted		1,107,342			1,047,689			31.83		17.76
Exercised		(421,983	)		(838,206	)		12.07		6.03
Forfeited		(18,750	)		—			7.57		—
Expired		—			(22,302	)		—		22.68
Cancelled		—			—			—		—
Options outstanding, end of period		7,409,881			6,360,976			13.87		8.38
Options exercisable, end of period		3,121,874			3,093,225			7.61		6.05

Options to Non-Employees

	Three Months					Six Months
	Ended June 30,					Ended June 30,
	2011		2010			2011			2010
Average risk-free interest rate		n/a		3.12	%		2.38	%		3.10	%
Contractual option life		n/a	6.84 years			6 years			6 - 6.84 years
Average expected volatility		n/a		61.00	%		50	%		61	%
Dividend yield		n/a		0.00	%		0	%		0	%

Fair value measurement of stock appreciation rights

	As at June 30, 2011		As at December 31, 2010
Average risk-free interest rate		2.25%		0.65%
Expected option life (in years)		0.36 - 2.40		0.24 - 2.51
Expected volatility		50%		50% - 61%
Annual termination probability		8.31%		0% - 8.31%
Dividend yield		0%		0%

Basic and diluted per-share computations

	Three Months				Six Months
	Ended June 30,				Ended June 30,
	2011		2010		2011		2010
Net income from operations applicable to common shareholders	$	1,825	$	13,302	$	822	$	39,883
Weighted average number of common shares (000’s):
Issued and outstanding, beginning of period		64,255		63,460		64,146		62,832
Weighted average number of shares issued during the period		121		104		136		478
Weighted average number of shares used in computing basic income per share		64,376		63,564		64,282		63,310
Assumed exercise of stock options, net of shares assumed		4,323		3,424		4,096		3,184
Weighted average number of shares used in computing diluted income per share		68,699		66,988		68,378		66,494

Movement of Shareholders' Equity

Balance as at December 31, 2010	$	158,458
Issuance of common shares for stock options exercised		5,095
Net income		822
Adjustment to other equity for employee stock options granted		4,797
Adjustment to other equity for non-employee stock options granted		2,232
Adjustment to capital stock for stock options exercised		2,210
Adjustment to other equity for stock options exercised		(2,210	)
Adjustments to accumulated other comprehensive income to record unrealized hedging gains		351
Adjustments to accumulated other comprehensive income to record the realization of hedging gains upon settlement		(724	)
Adjustments to accumulated other comprehensive income to record the amortization of actuarial loss on defined benefit plan		107
Adjustments to accumulated other comprehensive income to record an unrealized decline in the market value of the preferred stock of another business venture		(488	)
Tax effect of movement in accumulated other comprehensive income		136
Balance as at June 30, 2011	$	170,786