Acquisition of Business - Assets acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 29, 2017	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Cash	$ 4,142
Accounts receivable	27,819
Inventories	3,096
Fixed assets	43,689
Intangible assets:
Other assets	5,310
Accounts payable and accrued liabilities	(25,272)
Deferred taxes	(5,270)
Other liabilities	(750)
Total identifiable net assets	69,487
Goodwill	61,299	$ 0	$ 61,299
Total consideration transferred	130,786
Noncompete Agreements [Member]
Intangible assets:
Intangible assets	$ 900
Weighted average useful life of intangible assets	5 years
Customer Relationships [Member]
Intangible assets:
Intangible assets	$ 11,622
Weighted average useful life of intangible assets	15 years
Trade Names [Member]
Intangible assets:
Intangible assets	$ 4,201
Weighted average useful life of intangible assets	7 years