Convertible Senior Notes - Interest Expense Recognized Related to Notes Prior to Capitalization of Interest (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 27, 2014	Dec. 28, 2013
Debt Disclosure [Abstract]
Contractual interest expense	$ 2,626	$ 1,539
Amortization of debt issuance costs	665us-gaap_AmortizationOfFinancingCosts	358us-gaap_AmortizationOfFinancingCosts
Amortization of debt discount	7,730	4,164
Total interest expense recognized related to notes prior to capitalization of interest	$ 11,021us-gaap_InterestExpenseDebt	$ 6,061us-gaap_InterestExpenseDebt

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of noncash expense included in interest expense to issue debt and obtain financing associated with the related debt instruments. Alternate captions include noncash interest expense.

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

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Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

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