Fair Value Measurements (Tables)

12 Months Ended

Dec. 30, 2017

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 December 30, 2017 and December 31, 2016 were as follows:

	December 30, 2017				December 31, 2016
(in millions of U.S. dollars)	Carrying Value		Fair Value		Carrying Value		Fair Value
6.750% senior notes due in 2020 1, 3	$	—	$	—	$	615.7	$	647.7
10.000% senior notes due in 2021 1, 2		269.9		283.4		384.2		383.7
5.375% senior notes due in 2022 1, 3		519.0		539.9		517.9		534.2
5.500% senior notes due in 2024 1, 3		529.6		574.0		464.3		505.5
5.500% senior notes due in 2025 1, 3		739.0		759.3		—		—
Total	$	2,057.5	$	2,156.6	$	1,982.1	$	2,071.1

^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 and $34.2 million at December 30, 2017 and December 31, 2016, respectively.

^3. Carrying value of our significant outstanding debt is net of unamortized debt issuance costs as of December 30, 2017 and December 31, 2016 (see Note 15 to the Consolidated Financial Statements).