Goodwill and Other Intangible Assets (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Oct. 01, 2011
Goodwill [Roll Forward]
Balance, beginning of period	$ 178,516,000	$ 176,923,000
Acquired goodwill	137,000	1,164,000
Purchase price adjustments, net		429,000
Goodwill impairment	(1,550,000)	0	(310,000)
Balance, end of period	177,103,000	178,516,000	176,923,000
Accumulated goodwill impairment losses		700,000	700,000
Number of reporting units with allocated goodwill balances				209
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, gross	26,888,000	26,888,000
Less accumulated amortization	(15,150,000)	(13,923,000)
Other intangible assets, net	11,738,000	12,965,000
Other intangible amortization expense	1,200,000	1,900,000	1,800,000
Other intangible assets, future amortization expense [Abstract]
2012	854,000
2013	790,000
2014	647,000
2015	135,000
2016	75,000
NPT tradename [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	1,500,000	1,500,000
Finite-lived intangible assets, average useful life (in years)	20.0000
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	10,223,000	10,223,000
Finite-lived intangible assets, average useful life (in years)	5.0000
Employment Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	650,000	650,000
Distribution Agreement [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	6,115,000	6,115,000
Horizon tradename [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Indefinite-lived intangible assets	8,400,000	8,400,000
Reporting unit [Member]
Goodwill [Line Items]
Highest goodwill balance, UK reporting unit				7,100,000
Highest goodwill balance among other reporting units, excluding UK reporting unit				5,700,000
Average goodwill balance among other reporting units, excluding UK reporting unit				800,000
Total goodwill balance				4,600,000