12. Convertible debentures

The following table provides details related to outstanding convertible debentures:


	6.5%		6.25%		5.6%		5.75%		6.00%
	Debentures		Debentures		Debentures		Debentures		Debentures
	due		due		due		due		due
	October 2014		March 2017		June 2017		June 2019		December 2019		Total
Balance at December 31, 2013	$	42.1	$	63.4	$	75.7	$	130.0	$	94.0	$	405.2
Repayment of convertible debentures		(40.6)		—		(0.7)		(1.3)		(0.4)		(43.0)
Foreign exchange gain		(1.5)		(5.3)		(6.4)		—		(7.6)		(20.8)
Gain on repurchase of convertible debentures		—		(0.1)		—		(0.4)		(0.3)		(0.8)
Balance at December 31, 2014	$	—	$	58.0	$	68.6	$	128.3	$	85.7	$	340.6
Repayment of convertible debentures		—		(0.1)		(3.0)		(9.4)		(6.4)		(18.9)
Foreign exchange (gain) loss		—		(9.3)		(10.7)		—		(13.2)		(33.2)
Gain on repurchase of convertible debentures		—		—		(0.1)		(1.9)		(1.1)		(3.1)
Balance at December 31, 2015	$	—	$	48.6	$	54.8	$	117.0	$	65.0	$	285.4

Aggregate interest expense related to the convertible debentures was $17.2 million, $22.8 million, and $24.2 million for the years ended December 31, 2015, 2014, and 2013, respectively.

In 2006 we issued, in a public offering, Cdn$60.0 million aggregate principal amount of 6.25% convertible secured debentures (the “2006 Debentures”) for gross proceeds of $52.8 million. The 2006 Debentures paid interest semi‑annually on April 30 and October 31 of each year, had an initial maturity date of October 31, 2011 and were convertible into approximately 80.6452 common shares per Cdn$1,000 principal amount of 2006 Debentures, at any time, at the option of the holder, representing a conversion price of Cdn$12.40 per common share. The 2006 Debentures were secured by a subordinated pledge of our interest in certain subsidiaries and contain certain restrictive covenants. In connection with our conversion to a common share structure on November 27, 2009, the holders of the 2006 Debentures approved an amendment to increase the annual interest rate from 6.25% to 6.50% and separately, an extension of the maturity date from October 2011 to October 2014. Over the maturity term of the 2006 Debentures, Cdn$15.2 million of the 2006 Debentures were converted to 1.2 million common shares. On October 31, 2014, we used Cdn$44.8 million of cash on hand to repay the 2006 Debentures at maturity.

On December 17, 2009, we issued, in a public offering, Cdn$86.3 million aggregate principal amount of 6.25% convertible unsecured debentures (the “2009 Debentures”) for gross proceeds of $82.1 million. The 2009 Debentures pay interest semi‑annually on March 15 and September 15 of each year. The 2009 Debentures mature on March 15, 2017 and are convertible into approximately 76.9231 common shares per Cdn$1,000 principal amount of 2009 Debentures, at any time, at the option of the holder, representing a conversion price of Cdn$13.00 per common share. As of December 31, 2015, a cumulative Cdn$18.8 million of the 2009 Debentures, have been converted to 1.4 million common shares.

On October 20, 2010, we issued, in a public offering, Cdn$80.5 million aggregate principal amount of 5.60% convertible unsecured subordinated debentures (the “2010 Debentures”) for gross proceeds of $78.9 million. The 2010 Debentures pay interest semi‑annually on June 30 and December 30 of each year. The 2010 Debentures mature on June 30, 2017, unless earlier redeemed. The debentures are convertible into our common shares at an initial conversion rate of 55.2486 common shares per Cdn$1,000 principal amount of 2010 Debentures, at any time, at the option of the holder, representing an initial conversion price of approximately Cdn$18.10 per common share.

On July 5, 2012, we issued, in a public offering, $130.0 million aggregate principal amount of 5.75% convertible unsecured subordinated debentures due June 30, 2019 (the “July 2012 Debentures”) for net proceeds of $124.0 million. The July 2012 Debentures pay interest semi‑annually on the last day of June and December of each year. The July 2012 Debentures are convertible into our common shares at an initial conversion rate of 57.9710 common shares per $1,000 principal amount of July 2012 debentures representing a conversion price of $17.25 per common share. We used the proceeds to fund a portion of our equity commitment in Canadian Hills.

On December 11, 2012, we issued, in a public offering, Cdn$100 million aggregate principal amount of 6.00% convertible unsecured subordinated debentures due December 31, 2019 (the “December 2012 Debentures”) for net proceeds of Cdn$95.5 million. The December 2012 Debentures pay interest semi‑annually on the last day of June and December of each year beginning June 30, 2013. The December 2012 Debentures are convertible into our common shares at an initial conversion rate of 68.9655 common shares per Cdn$1,000 principal amount of December 2012 Debentures representing a conversion price of Cdn$14.50 per common share. We used the proceeds to acquire all of the outstanding shares of capital stock of Ridgeline and to fund certain working capital commitments and acquisition expenses related to Ridgeline.

On November 11, 2014, we commenced a normal course issuer bid (“NCIB”) for our convertible debentures. Under the NCIB, we entered into a pre-defined automatic securities purchase plan with our broker in order to facilitate purchases of our convertible debentures which expired on November 10, 2015. As of December 31, 2015, we had repurchased and cancelled $24.8 million of convertible debentures and recorded a gain of $3.1 million in the consolidated statement of operations related to these transactions. On December 29, 2015, we commenced a new NCIB, which will expire on December 28, 2016. The actual amount of convertible debentures that may be purchased under the NCIB is approximately $28.5 million and is further limited to 10% of the public float of our convertible debentures.