Banking Facilities and Debt (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Summary of outstanding debt
Total Debt	$ 16,667,000us-gaap_LongTermDebt	$ 21,667,000us-gaap_LongTermDebt
Less current installments	16,667,000us-gaap_LongTermDebtCurrent	5,000,000us-gaap_LongTermDebtCurrent
Debt, excluding current installments		16,667,000us-gaap_LongTermDebtNoncurrent
Principal amounts payable on the long-term debt outstanding
2015	16,667,000
Total Debt	16,667,000us-gaap_LongTermDebt	21,667,000us-gaap_LongTermDebt
Interest rate swaps
Interest rate hedges
Interest rate swap liabilities	700,000	1,500,000
Interest rate swap liabilities included in accrued expenses	700,000	900,000
Interest rate swap liabilities included in other liabilities	0	600,000
Quarterly settlement payment pursuant to hedges	900,000	1,100,000
LIBOR
Banking facilities and other debt
Interest rate basis	LIBOR
Lender's prime rate
Banking facilities and other debt
Interest rate basis	Lender's Prime Rate
Minimum \| LIBOR
Banking facilities and other debt
Interest rate margin (as a percent)	1.75%
Minimum \| Lender's prime rate
Banking facilities and other debt
Interest rate margin (as a percent)	0.00%
Maximum
Banking facilities and other debt
Pro forma Cash Flow Leverage Ratio to be maintained to purchase, redeem or otherwise acquire shares of common stock	3.00
Cash flow leverage ratio	3.25
Maximum \| LIBOR
Banking facilities and other debt
Interest rate margin (as a percent)	2.75%
Maximum \| Lender's prime rate
Banking facilities and other debt
Interest rate margin (as a percent)	1.00%
Term Loan
Banking facilities and other debt
Term	10 years
Face amount of term loan	40,000,000
Quarterly principal payments	833,000
Final principal payment	7,500,000
Summary of outstanding debt
Total Debt	10,000,000	13,334,000
Principal amounts payable on the long-term debt outstanding
Total Debt	10,000,000	13,334,000
Term Loan \| LIBOR \| Interest rate swaps
Interest rate hedges
LIBOR (as a percent)	4.695%
Current interest rate (as a percent)	6.445%
Draw Term Loan
Banking facilities and other debt
Term	10 years
Face amount of term loan	20,000,000
Quarterly principal payments	417,000
Final principal payment	5,400,000
Summary of outstanding debt
Total Debt	6,667,000	8,333,000
Principal amounts payable on the long-term debt outstanding
Total Debt	6,667,000	8,333,000
75% of the outstanding balance of the Draw Term Loan \| Interest rate swaps
Interest rate hedges
Percentage of outstanding balance of debt hedged	75.00%
75% of the outstanding balance of the Draw Term Loan \| LIBOR \| Interest rate swaps
Interest rate hedges
LIBOR (as a percent)	4.875%
Current interest rate (as a percent)	6.625%
25% of the outstanding balance of the Draw Term Loan \| Interest rate swaps
Interest rate hedges
Percentage of outstanding balance of debt hedged	25.00%
25% of the outstanding balance of the Draw Term Loan \| LIBOR \| Interest rate swaps
Interest rate hedges
LIBOR (as a percent)	5.50%
Current interest rate (as a percent)	7.25%
Revolving Facility
Banking facilities and other debt
Maximum borrowing capacity	30,000,000
Letters of credit outstanding	$ 710,000
Revolving Facility \| Minimum
Banking facilities and other debt
Commitment fee (as a percent)	0.25%
Revolving Facility \| Maximum
Banking facilities and other debt
Commitment fee (as a percent)	0.40%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

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Face (par) amount of debt instrument at time of issuance.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Amount of the required periodic payments applied to principal.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Percentage of an entity's outstanding debt that is designated as a hedged item in cash flow, fair value, or net investment hedge.

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Represents the cash flow leverage ratio required under the terms of the credit agreement.

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Represents the pro forma cash flow leverage ratio required to be maintained by the entity to purchase, redeem or otherwise acquire shares of its common stock.

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Represents the reference rate for the variable rate of the interest rate derivative.

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Represents the final principal payment required to settle a long-term debt obligation.

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