Share Capital (Tables)

12 Months Ended

Dec. 31, 2011

Dec. 31, 2010

Share Capital [Abstract]

Stock options outstanding

The following options are outstanding as of December 31, 2011:

	Number of Outstanding Options			Weighted Average Exercise Price $/Option			Number of Nonvested Options			Weighted Average Grant-Date Fair Value $/Option
Balance, December 31, 2010		10,943,058		$	3.49			5,516,691		$	2.68
Granted in 2011		4,215,996			7.94			4,215,996			4.84
Exercised in 2011		(1,695,049	)		(2.70	)		-			-
Vested in 2011		-			-			(2,940,822	)		(2.26	)
Forfeited in 2011		(600,003	)		(6.70	)		(576,669	)		(4.06	)
Balance, December 31, 2011		12,864,002		$	4.90			6,215,196		$	4.22

Assumptions used to estimate the fair value of stock option awards

The fair value of each stock option award is estimated on the date of grant using the Black-Scholes option pricing model based on assumptions noted in the following table.

	Year Ended December 31,
	2011			2010			2009
Dividend yield (per share)	$nil			$nil			$nil
Volatility	75% to 81%			84% to 90%			94% to 98%
Weighted average volatility		80	%		89	%		96	%
Risk-free interest rate	0.4% to 1.4%			0.2% to 0.5%			0.4% to 0.6%
Weighted average risk-free interest rate		1.2	%		0.3	%		0.5	%
Expected term	4 to 6 years			3 years			3 years

Weighted average shares outstanding

Weighted average shares outstanding	Year Ended December 31,
	2011			2010			2009
Weighted average number of common and exchangeable shares outstanding		273,491,564			253,697,076			241,258,568
Shares issuable pursuant to warrants		2,708,183			3,750,781			9,503,818
Shares issuable pursuant to stock options		5,143,498			7,402,966			5,797,322
Shares to be purchased from proceeds of stock options		(56,243	)		(545,992	)		(2,969,605	)
Weighted average number of diluted common and exchangeable shares outstanding		281,287,002			264,304,831			253,590,103

Range of exercise prices of stock options outstanding

The table below summarizes stock options outstanding at December 31, 2011:

Range of Exercise Prices ($/option)	Number of Outstanding Options		Weighted Average Exercise Price $/Option		Weighted Average Expiry Years
0.50 to 2.00		1,195,837		1.12		4.6
2.01 to 3.50		4,310,250		2.47		6.8
3.51 to 5.50		621,666		4.52		8.3
5.51 to 7.00		3,132,753		5.94		8.4
7.01 to 8.40		3,603,496		8.23		9.1
Total		12,864,002	$	4.90		7.7

Exercisable stock options

The table below summarizes exercisable stock options at December 31, 2011:

Range of Exercise Prices ($/option)	Number of Exercisable Options	Weighted AverageExercise Price $/Option		Weighted Average Expiry Years
0.50 to 2.00	1,195,837	$	1.12	4.6
2.01 to 3.50	4,128,583	$	2.47	6.8
3.51 to 5.50	283,332	$	4.47	7.8
5.51 to 7.00	897,721	$	5.90	8.2
7.01 to 8.40	143,333	$	7.67	7.2
Total	6,648,806	$	2.89	6.6