Debt and Credit Facility (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of Interest Incurred on Convertible Debt

The following table provides additional information regarding the Convertible Notes (in millions of dollars):

	Year Ended December 31,
	2015
Contractual coupon interest	$	2.0
Amortization of discount	2.4
Amortization of debt issuance costs	0.3
Total interest expense1	$	4.7

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^1.  A portion of the interest relating to the Convertible Notes was capitalized as construction in progress.