Fair Value Measurements Non-Recurring Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Impairment of Long-Lived Assets Held-for-use	$ 165	$ 17
Impairment of Long-Lived Assets to be Disposed of	41	$ 493
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Assets Held and Used, Long Lived, Fair Value Disclosure	0		$ 757
Assets Held-for-sale, Long Lived, Fair Value Disclosure	427		1,560
Total	427		2,317
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Assets Held and Used, Long Lived, Fair Value Disclosure	0		0
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0		0
Total	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Assets Held and Used, Long Lived, Fair Value Disclosure	0		0
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0		0
Total	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Assets Held and Used, Long Lived, Fair Value Disclosure	0		757
Assets Held-for-sale, Long Lived, Fair Value Disclosure	427		1,560
Total	$ 427		$ 2,317