Goodwill and Other Intangible Assets (Details)		3 Months Ended		12 Months Ended
	Jan. 01, 2018 USD ($) item	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) item
Goodwill
Balance at the beginning of the period	$ 346,168,000	$ 346,168,000
Balance at the end of the period		346,168,000		$ 346,168,000
Goodwill, Impairment Loss		0
Other intangible assets
Cost		127,929,000		127,929,000
Accumulated Amortization		(109,132,000)		(107,108,000)
Total		18,797,000		20,821,000
Cost		293,929,000		293,929,000
Accumulated Impairment		(34,900,000)		(34,900,000)
Net		149,897,000		$ 151,921,000
Total amortization expense		2,000,000	$ 3,000,000
Number of reporting segments | item	1			3
Trade names
Other intangible assets
Cost		166,000,000		$ 166,000,000
Net		131,100,000		131,100,000
Accumulated Impairment		(34,900,000)		(34,900,000)
Customer relationship
Other intangible assets
Cost		125,828,000		125,828,000
Accumulated Amortization		(107,842,000)		(105,911,000)
Total		17,986,000		19,917,000
Non-compete agreements
Other intangible assets
Cost		2,101,000		2,101,000
Accumulated Amortization		(1,290,000)		(1,197,000)
Total		$ 811,000		$ 904,000