Debt Instrument, Discount Percent

No definition available.

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Balance Type:	na
Period Type:	instant

- 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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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationPeriod
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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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Balance Type:
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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Notes Payable (Narrative) (Details) $ in Thousands		6 Months Ended
Notes Payable (Narrative) (Details) $ in Thousands	Mar. 29, 2017 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Mar. 08, 2017 USD ($)
Debt Instrument [Line Items]
Interest rate				4.40%
Debt issuance cost				$ 3,400
Debt instrument, discount percent				99.847%
Effective interest rate				4.45%
Debt to total capital ratio		0.180
Unamortized debt issuance cost		$ 200
Unsecured Notes Two [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Loan maximum borrowing capacity	$ 50,000
Revolving credit facility term	5 years
Unsecured Notes Two [Member] \| Revolving Credit Facility [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt to total capital ratio	0.15
Commitment fee on undrawn portion of facility	0.125%	0.15%
Unsecured Notes Two [Member] \| Revolving Credit Facility [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt to total capital ratio	0.25
Commitment fee on undrawn portion of facility	0.225%
Unsecured Notes Two [Member] \| Revolving Credit Facility [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.125%
Debt to total capital ratio	0.15
Unsecured Notes Two [Member] \| Revolving Credit Facility [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.625%
Debt to total capital ratio	0.25
Level 2 [Member] \| Borrowings [Member] \| Unsecured Notes One [Member] \| Unsecured debt [Member]
Debt Instrument [Line Items]
Unsecured debt		$ 375,000	$ 375,000
Interest rate		4.40%
Level 2 [Member] \| Borrowings [Member] \| Unsecured Notes Two [Member] \| Unsecured debt [Member]
Debt Instrument [Line Items]
Unsecured debt		$ 0	$ 0
Level 2 [Member] \| Borrowings [Member] \| Unsecured Notes Two [Member] \| Unsecured debt [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		0.1125%
Level 2 [Member] \| Borrowings [Member] \| Unsecured Notes Two [Member] \| Unsecured debt [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		0.1625%