Revenues Impact of Adoption on Consolidated Statement of Cash Flow (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 25, 2019	Sep. 25, 2019	Jun. 26, 2019	Mar. 27, 2019	Dec. 26, 2018	Sep. 26, 2018	Jun. 27, 2018	Mar. 28, 2018	Dec. 25, 2019	Dec. 26, 2018	Dec. 27, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net income	$ 18,559	$ 49,122	$ 34,239	$ 15,490	$ 11,503	$ 10,805	$ 11,626	$ 9,759	$ 117,410	$ 43,693	$ 39,594
Deferred income tax expense									16,005	6,193	10,271
Other current assets									(4,108)	921	(2,380)
Other accrued liabilities									(4,144)	(1,676)	135
Other noncurrent liabilities									1,898	(4,418)	(3,113)
Net cash flows provided by operating activities									$ 43,327	73,690	$ 78,269
Adjustments | Adjustments
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net income					(148)					(1,147)
Deferred income tax expense										(400)
Other current assets										(509)
Other accrued liabilities										573
Other noncurrent liabilities										1,483
Net cash flows provided by operating activities										0
Amounts without adoption of Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net income					$ 11,355					42,546
Deferred income tax expense										5,793
Other current assets										412
Other accrued liabilities										(1,103)
Other noncurrent liabilities										(2,935)
Net cash flows provided by operating activities										$ 73,690