Fair Value Measurements (Fair value measurements on a recurring basis) (Details) - USD ($) $ in Thousands | Sep. 27, 2015 | Dec. 28, 2014 |
Fair value, inputs, level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets at fair value | $ 14,245 | $ 15,804 |
Liabilities at fair value | 0 | 0 |
Fair value, inputs, level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets at fair value | 0 | 0 |
Liabilities at fair value | 14,233 | 4,490 |
Fair value, measurements, recurring [Member] | Fair value, inputs, level 1 [Member] | Accrued and other current liabilities [Member] | Interest rate swap [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative liability, current | 0 | 0 |
Fair value, measurements, recurring [Member] | Fair value, inputs, level 1 [Member] | Accrued and other current liabilities [Member] | Commodity [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative liability, current | 0 | 0 |
Fair value, measurements, recurring [Member] | Fair value, inputs, level 1 [Member] | Other long-term liabilities, net [Member] | Interest rate swap [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Financial liabilities fair value disclosure | 0 | 0 |
Fair value, measurements, recurring [Member] | Fair value, inputs, level 2 [Member] | Accrued and other current liabilities [Member] | Interest rate swap [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative liability, current | 6,104 | 2,617 |
Fair value, measurements, recurring [Member] | Fair value, inputs, level 2 [Member] | Accrued and other current liabilities [Member] | Commodity [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative liability, current | 577 | 566 |
Fair value, measurements, recurring [Member] | Fair value, inputs, level 2 [Member] | Other long-term liabilities, net [Member] | Interest rate swap [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Financial liabilities fair value disclosure | 7,552 | 1,307 |
Fixed income funds [Member] | Fair value, measurements, recurring [Member] | Fair value, inputs, level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash and cash equivalents, fair value disclosure | 3,888 | 4,602 |
Restricted cash equivalents, fair value disclosure | 551 | 0 |
Fixed income funds [Member] | Fair value, measurements, recurring [Member] | Fair value, inputs, level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash and cash equivalents, fair value disclosure | 0 | 0 |
Restricted cash equivalents, fair value disclosure | 0 | 0 |
Money market funds [Member] | Fair value, measurements, recurring [Member] | Fair value, inputs, level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash and cash equivalents, fair value disclosure | 9,741 | 7,842 |
Restricted cash equivalents, fair value disclosure | 65 | 3,360 |
Money market funds [Member] | Fair value, measurements, recurring [Member] | Fair value, inputs, level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash and cash equivalents, fair value disclosure | 0 | 0 |
Restricted cash equivalents, fair value disclosure | 0 | 0 |
Reported value measurement [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets at fair value | 14,245 | 15,804 |
Liabilities at fair value | 14,233 | 4,490 |
Reported value measurement [Member] | Fair value, measurements, recurring [Member] | Accrued and other current liabilities [Member] | Interest rate swap [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative liability, current | 6,104 | 2,617 |
Reported value measurement [Member] | Fair value, measurements, recurring [Member] | Accrued and other current liabilities [Member] | Commodity [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative liability, current | 577 | 566 |
Reported value measurement [Member] | Fair value, measurements, recurring [Member] | Other long-term liabilities, net [Member] | Interest rate swap [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Financial liabilities fair value disclosure | 7,552 | 1,307 |
Reported value measurement [Member] | Fixed income funds [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash and cash equivalents, fair value disclosure | 3,888 | 4,602 |
Restricted cash equivalents, fair value disclosure | 551 | 0 |
Reported value measurement [Member] | Money market funds [Member] | Fair value, measurements, recurring [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash and cash equivalents, fair value disclosure | 9,741 | 7,842 |
Restricted cash equivalents, fair value disclosure | $ 65 | $ 3,360 |