Long-Term Debt (Long-term Debt Table) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Accumulated Amortization, Debt Issuance Costs	$ 4,366,000		$ 4,366,000		$ 4,138,000
Revolving credit facility, maximum borrowing capacity	300,000,000		300,000,000
Debt issuance costs	(1,043,000)		(1,043,000)		(1,270,000)
Current maturities on long-term debt	(16,126,000)		(16,126,000)		(13,021,000)
Long-term debt, excluding current maturities	199,992,000		199,992,000		204,404,000
Revolving credit facility present accordion provisions	75,000,000		75,000,000
Amortization of Debt Issuance Costs			614,000	$ 622,000
Credit Agreement [Member]
Debt Instrument [Line Items]
Amortization of Debt Issuance Costs	100,000	$ 100,000	200,000	$ 300,000
Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Carrying value of the liability component					67,700,000
Credit Agreement [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Carrying value of the liability component	130,313,000		130,313,000		138,750,000
Current maturities on long-term debt	(14,063,000)		(14,063,000)		(11,250,000)
Notes Payable, Other Payables [Member] | Acquisition Debt, Deferred Purchase Price [Member]
Debt Instrument [Line Items]
Carrying value of the liability component	11,348,000		11,348,000		12,245,000
Current maturities on long-term debt	$ (2,063,000)		$ (2,063,000)		$ (1,771,000)
Term Number Two [Member]
Debt Instrument [Line Items]
Ratio of indebtedness to net capital (in Ratio) (below at March 31, 2015)	3.5		3.5