Banking Facilities and Debt (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Summary of outstanding debt
Debt	$ 19,167,000		$ 19,167,000		$ 21,667,000
Less current installments	5,000,000		5,000,000		5,000,000
Debt, excluding current installments	14,167,000		14,167,000		16,667,000
Interest Rate Swap [Member]
Interest rate hedges
Interest rate swap liabilities	1,100,000		1,100,000		1,500,000
Interest rate swap liabilities included in accrued expenses	800,000		800,000		900,000
Interest rate swap liabilities included in other liabilities	300,000		300,000		600,000
Quarterly settlement payment pursuant to hedges	200,000	300,000	500,000	600,000
London Interbank Offered Rate (LIBOR) [Member]
Banking facilities and other debt
Interest rate basis			LIBOR
Prime Rate [Member]
Banking facilities and other debt
Interest rate basis			Lender's Prime Rate
Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Banking facilities and other debt
Interest rate margin (as a percent)			1.75%
Minimum [Member] | Prime Rate [Member]
Banking facilities and other debt
Interest rate margin (as a percent)			0.00%
Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Banking facilities and other debt
Interest rate margin (as a percent)			2.75%
Maximum [Member] | Prime Rate [Member]
Banking facilities and other debt
Interest rate margin (as a percent)			1.00%
Term Loan [Member]
Banking facilities and other debt
Term			10 years
Face amount of term loan	40,000,000		40,000,000
Quarterly principal payments			800,000
Final principal payment			10,000,000
Summary of outstanding debt
Debt	11,667,000		11,667,000		13,334,000
Term Loan [Member] | London Interbank Offered Rate (LIBOR) [Member] | Interest Rate Swap [Member]
Interest rate hedges
LIBOR (as a percent)			4.695%
Current interest rate (as a percent)	6.445%		6.445%
Draw Term Loan [Member]
Banking facilities and other debt
Term			10 years
Face amount of term loan	20,000,000		20,000,000
Quarterly principal payments			400,000
Final principal payment			6,700,000
Summary of outstanding debt
Debt	7,500,000		7,500,000		8,333,000
Seventy Five Percent of Outstanding Balance of Draw Term Loan [Member] | Interest Rate Swap [Member]
Interest rate hedges
Percentage of outstanding balance of debt hedged	75.00%		75.00%
Seventy Five Percent of Outstanding Balance of Draw Term Loan [Member] | London Interbank Offered Rate (LIBOR) [Member] | Interest Rate Swap [Member]
Interest rate hedges
LIBOR (as a percent)			4.875%
Current interest rate (as a percent)	6.625%		6.625%
Twenty Five Percent of Outstanding Balance of Draw Term Loan [Member] | Interest Rate Swap [Member]
Interest rate hedges
Percentage of outstanding balance of debt hedged	25.00%		25.00%
Twenty Five Percent of Outstanding Balance of Draw Term Loan [Member] | London Interbank Offered Rate (LIBOR) [Member] | Interest Rate Swap [Member]
Interest rate hedges
LIBOR (as a percent)			5.50%
Current interest rate (as a percent)	7.25%		7.25%
Revolving Credit Facility [Member]
Banking facilities and other debt
Maximum borrowing capacity	30,000,000		30,000,000
Letters of credit outstanding	$ 700,000		$ 700,000		$ 700,000
Revolving Credit Facility [Member] | Minimum [Member]
Banking facilities and other debt
Commitment fee (as a percent)			0.25%
Revolving Credit Facility [Member] | Maximum [Member]
Banking facilities and other debt
Commitment fee (as a percent)			0.40%