Goodwill and Other Intangible Assets, Intangible Assets (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets, Net [Abstract]
Total acquired intangible assets		$ 98,871	$ 98,966
Less accumulated amortization	[1]	(51,391)	(43,853)
Net acquired intangible assets		47,480	55,113
Amortization of acquired intangible assets [Abstract]
Amortization expense		7,600	8,000	$ 7,100
Estimated amortization expense in year 2019		6,300
Estimated amortization expense in year 2020		5,900
Estimated amortization expense in year 2021		4,600
Estimated amortization expense in year 2022		3,000
Estimated amortization expense in years 2023 through 2031		22,500
Customer Relationships [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Total acquired intangible assets		87,195	87,290
Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Total acquired intangible assets		6,800	6,800
Intangible assets acquired [Abstract]
Amount of acquired indefinite-lived intangible assets		5,200
Non-Compete Agreements [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Total acquired intangible assets		3,193	3,193
Patents [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Total acquired intangible assets		723	723
Supply Agreement [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Total acquired intangible assets		800	800
Leaseholds [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Total acquired intangible assets		160	160
Computer Software [Member]
Other Intangible Assets [Abstract]
Other intangible assets		17,200	17,200
Accumulated computer software amortization		(16,300)	(16,100)
Amortization of computer software		$ 400	$ 500	$ 600
Computer Software [Member] | Minimum [Member]
Other Intangible Assets [Abstract]
Estimated useful life of intangible assets		3 years
Computer Software [Member] | Maximum [Member]
Other Intangible Assets [Abstract]
Estimated useful life of intangible assets		10 years

[1] Applies to all intangible assets, except for trademarks and trade names totaling $5.2 million, which have indefinite useful lives and, as such, are not being amortized.