Bank Debt (Narrative) (Details)	3 Months Ended
Mar. 31, 2018 USD ($)
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	3.00%
Debt instrument, interest rate, effective percentage	4.89%
Leverage ratio	237.00%
Debt service coverage ratio	169.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Amount of debt with maximum interest rate	$ 100,000,000
Percentage decrease in amount of debt with maximum interest rate per quarter after commencement date	10.00%
Date that the percentage of debt with a maximum interest rate begins to decrease quarterly	Mar. 31, 2016
Credit Agreement [Member]
Debt Instrument [Line Items]
Closing costs of debt	$ 9,100,000
Credit agreement, amount outstanding	191,000,000
Debt, unused borrowing capacity	64,000,000
Liquidity	$ 82,000,000
Debt instrument, interest rate, effective percentage	5.00%
Credit Agreement [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt service coverage ratio	125.00%
Credit Agreement [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	2.25%
Credit Agreement [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	4.00%
Credit Agreement [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit agreement, amount outstanding	$ 136,000,000
Credit facility, maximum borrowing capacity	200,000,000
Term Loan [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Credit agreement, amount outstanding	$ 55,000,000

Amount of debt with maximum interest rate

No definition available.

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- Definition

Date that the percentage of debt with a maximum interest rate begins to decrease quarterly

+ References

No definition available.

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- Definition

Debt service coverage ratio

+ References

No definition available.

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- Definition

Leverage Ratio

+ References

No definition available.

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- Definition

Liquidity

+ References

No definition available.

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- Definition

Percentage decrease in amount of debt with maximum interest rate

+ References

No definition available.

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- Definition

The net increase(decrease) in interest income during the period representing the allocation of deferred loan origination fees less deferred loan origination costs using the effective interest method over the term of the debt arrangement to which they pertain taking into account the effect of prepayments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

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

+ References

No definition available.

+ Details

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

+ References

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- Definition

Fair value of the amount outstanding under the credit facility.

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- Definition

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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