Common shares (Tables)

12 Months Ended

Dec. 31, 2013

Equity [Abstract]

Summary of Fair Value Option Pricing Model

The fair value of each option granted was estimated on the date of grant using the Black-Scholes-Merton fair value option pricing model with the following assumptions:

	2013		2012		2011
Risk-free interest rate		1.54%		1.52% – 1.74%		1.67% – 2.91%
Volatility factor of the future expected market price of the Company’s common shares		61.32%		56.40% – 57.20%		49.18% – 56.29%
Expected life of the options		6 years		6 years		6 years

Summary of Stock Options

Details of stock options are as follows:

	2013					2012
	Number			Weighted average exercise price		Number			Weighted average exercise price
Outstanding, beginning of year		742,800		$	11.80		841,900		$	11.70
Granted		41,100			6.51		67,000			6.52
Forfeited		(160,150	)		12.67		(98,100	)		14.01
Exercised		(66,000	)		5.25		(68,000	)		2.20
Outstanding, end of year		557,750		$	11.93		742,800		$	11.80
Exercisable, end of year		419,080		$	13.70		468,960		$	14.44

Summary of Range of Exercise Prices, Weighted Average Exercise Price and Weighted Average Remaining Contractual Life

At December 31, 2013, the range of exercise prices, the weighted average exercise price and the weighted average remaining contractual life are as follows:

	Options outstanding						Options exercisable
Range of exercise prices	Number outstanding		Weighted average remaining contractual life (years)		Weighted average exercise price		Number exercisable		Weighted average remaining contractual life (years)		Weighted average exercise price
$5.25 - $8.45		168,650		8.12	$	5.87		47,840		7.98	$	5.61
$9.80 - $18.99		389,100		2.90	$	14.56		371,240		2.73	$	14.75
$5.25 - $18.99		557,750		4.48	$	11.93		419,080		3.32	$	13.70