Properties And Equipment	12 Months Ended
	Dec. 31, 2021
Properties And Equipment [Abstract]
Properties And Equipment	12.    Properties and Equipment A summary of properties and equipment follows (in thousands): December 31, 2021 2020Land$ 11,348 $ 9,385Buildings and building improvements 122,762 117,419Transportation equipment 73,322 68,379Machinery and equipment 143,335 129,835Computer software 64,064 62,138Furniture and fixtures 78,979 78,507Projects under development 17,781 15,537Total properties and equipment 511,591 481,200Less accumulated depreciation (317,911) (293,380)Net properties and equipment$ 193,680 $ 187,820 The net book value of computer software at December 31, 2021 and 2020, was $9.0 million and $8.9 million, respectively. Depreciation expense for computer software was $5.8 million, $5.5 million and $4.6 million for the years ended December 31, 2021, 2020 and 2019, respectively.