Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Carrying Value and Estimated Fair Values of Outstanding Debt

The carrying values and estimated fair values of our significant outstanding debt as of March 31, 2018 and December 30, 2017 were as follows:

	March 31, 2018				December 30, 2017
(in millions of U.S. dollars)	Carrying Value		Fair Value		Carrying Value		Fair Value
10.000% senior notes due in 20211,2	$	—	$	—	$	269.9	$	283.4
5.375% senior notes due in 20221,3		—		—		519.0		539.9
5.500% senior notes due in 20241,3		545.6		579.7		529.6		574.0
5.500% senior notes due in 20251,3		739.3		730.1		739.0		759.3
Total	$	1,284.9	$	1,309.8	$	2,057.5	$	2,156.6

^1. The fair values were based on the trading levels and bid/offer prices observed by a market participant and are considered Level 2 financial instruments.

^2. Includes unamortized premium of $19.9 million at December 30, 2017.

^3. Carrying value of our significant outstanding debt is net of unamortized debt issuance costs as of March 31, 2018 and December 30, 2017 (see Note 10 to the Consolidated Financial Statements).