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Unsecured Line of Credit (Details) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 USD ($) yr mo | Dec. 31, 2015 USD ($)
Line of Credit Facility [Line Items] |  |
Line of Credit Facility, Current Borrowing Capacity | $ 1,000,000 |
Line of Credit Facility, Expiration Date | Jul. 26, 2018 |
Line of Credit Facility, Frequency of Commitment Fee Payment | quarterly |
Line of Credit Facility, Amount Outstanding | $ 0 | $ 0
Leverage Ratio, Maximum | 60.00% |
Leverage Ratio Maximum Increasing Limit | 65.00% |
Leverage Ratio Reduction Limit | 60.00% |
Leverage Ratio Reduction Period, Years | yr | 1 |
Maximum Secured Debt Leverage Ratio | 55.00% |
Fixed Charge Coverage Ratio Minimum. | 1.40 |
Maximum Unsecured Debt Leverage Ratio | 60.00% |
Unsecured Debt Leverage Ratio Maximum Increasing Limit | 65.00% |
Unsecured Debt Leverage Ratio Reduction Limit | 60.00% |
Unsecured Debt Leverage Ratio Reduction Period, Years | yr | 1 |
Unsecured Debt Interest Coverage Ratio Minimum. | 1.75 |
Alternative Base Interest Rate Calculation [Member] |  |
Line of Credit Facility [Line Items] |  |
Amount added to Federal Funds Rate to Calculate Interest Rate | 0.50% |
LIBOR Period Used to Calculate Interest Rate (in months) | mo | 1 |
Amount added to LIBOR to Calculate Interest Rate | 1.00% |
Maximum [Member] |  |
Line of Credit Facility [Line Items] |  |
Line of Credit Facility, Current Borrowing Capacity | $ 1,500,000 |
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage | 0.35% |
Maximum [Member] | Interest Rate Based on LIBOR or CDOR [Member] |  |
Line of Credit Facility [Line Items] |  |
Margin added to Calculated Interest Rate | 1.70% |
Maximum [Member] | Alternative Base Interest Rate Calculation [Member] |  |
Line of Credit Facility [Line Items] |  |
Margin added to Calculated Interest Rate | 0.70% |
Minimum [Member] |  |
Line of Credit Facility [Line Items] |  |
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage | 0.125% |
Minimum [Member] | Interest Rate Based on LIBOR or CDOR [Member] |  |
Line of Credit Facility [Line Items] |  |
Margin added to Calculated Interest Rate | 0.925% |
Minimum [Member] | Alternative Base Interest Rate Calculation [Member] |  |
Line of Credit Facility [Line Items] |  |
Margin added to Calculated Interest Rate | 0.00% |
Rate Based on Current Credit Rating [Member] |  |
Line of Credit Facility [Line Items] |  |
Line Of Credit Facility Extension Fee | 0.15% |
Rate Based on Current Credit Rating [Member] | Interest Rate Based on LIBOR or CDOR [Member] |  |
Line of Credit Facility [Line Items] |  |
Margin added to Calculated Interest Rate | 1.00% |
Rate Based on Current Credit Rating [Member] | Alternative Base Interest Rate Calculation [Member] |  |
Line of Credit Facility [Line Items] |  |
Margin added to Calculated Interest Rate | 0.00% |

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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 + Details
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- Definition Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Date the credit facility terminates, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Description of when the fee for available but unused credit capacity is required to be paid (for example, annually, quarterly, or monthly). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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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. + Details
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- 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
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