Share capital (Tables)

9 Months Ended

Sep. 30, 2016

Stockholders' Equity Note [Abstract]

Summary of preferred shares issued and outstanding

The following table is a summary of the Preferred shares issued and outstanding:

	Preferred Shares
Preferred shares issued and outstanding, December 31, 2015	—
Preferred shares issued	6,000
Preferred shares issued and outstanding, September 30, 2016	6,000

Summary of common shares issued and outstanding

The following table is a summary of the common share activity during the nine months endedSeptember 30, 2016 and 2015 :

	Share Activity During the Nine Months Ended September 30,
	2016		2015
Common shares issued, beginning of period	160,570,772		155,554,224
Restricted share awards vested, net of shares withheld	608,024		610,714
Restricted share units vested, net of shares withheld	18,486		13,260
Options exercised	27,983		782,465
Warrants exercised	—		1,461,715
Direct issuance of common stock	—		639
Performance share awards vested, net of shares withheld	48,088		11,524
Common shares issued, end of period	161,273,353		158,434,541
Treasury shares, end of period	(81,830,323	)	(76,436,650	)
Common shares outstanding, end of period	79,443,030		81,997,891