Acquisition of Millis Transfer (Details) - USD ($) $ in Thousands		12 Months Ended
	Aug. 26, 2019	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs		$ 500
Accounts and Other Receivables, Net, Current	$ 14,474
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other	1,656
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	117,060
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	802
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	15,300
Business Combination, Recognized Identifiable Assets Acquired, Goodwill	35,885
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	185,177
Self Insurance Reserve	4,371
Payments to Acquire Businesses, Net of Cash Acquired	61,927
Accounts Payable and Accrued Liabilities	31,737
Long-term Debt	70,191
Business Combination, Total Consideration	156,000
Business Combination, Cash and Equity Transferred	62,677
Noncash or Part Noncash Acquisition, Debt Assumed	93,300
Acquired Business Percent of Assets		21.10%
Acquired Business Percent of Revenue		8.80%
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	750
Deferred Taxes	$ 16,201
Debt, Long-term and Short-term, Combined Amount		$ 0
Business Combination, Pro Forma Information, Net Income Change		3,000	$ 3,600
Business Acquisition, Pro Forma Revenue		694,672	760,917
Business Acquisition, Pro Forma Net Income (Loss)		$ 75,951	$ 76,259