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Organization and Summary of Significant Accounting Policies (Investments and Lease Costs) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | May 25, 2017
Investments |  |  |  |
Ownership interest (as a percent) | 50.00% |  |  |
Initial Direct Costs associated with Leases |  |  |  |
Amortization of initial direct costs associated with leases | $ 1.8 | $ 1.6 | $ 1.6 |
WOLF |  |  |  |
Investments |  |  |  |
Previously held interest (as a percent) | 50.00% |  |  |
WMES |  |  |  |
Investments |  |  |  |
Ownership interest (as a percent) | 100.00% |  |  | 50.00%

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- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571 + Details
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