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Benefit Plans (Details) - USD ($) $ in Thousands | 12 Months Ended | 24 Months Ended
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Jun. 30, 2018 | Dec. 31, 2017 | Jun. 30, 2017 | Jun. 30, 2019
Multiemployer Plans [Line Items] |  |  |  |  |  |
Plan contributions | $ 14,160 | $ 13,433 |  | $ 16,745 |  |
401 (K) Plan |  |  |  |  |  |
Employee contribution limit per calendar year | 15.00% |  |  |  |  |
Employer matching contribution, percent of match | 100.00% | 100.00% |  | 50.00% |  |
Percentage of eligible compensation matched by employer | 4.00% | 4.00% |  | 6.00% |  |
Matching contribution | $ 1,600 | $ 1,100 |  | $ 1,000 |  |
Health Plan |  |  |  |  |  |
Multiemployer Plans [Line Items] |  |  |  |  |  |
Plan contributions | $ 9,949 | 9,310 |  | 11,426 |  |
Multiemployer plan, contributions by employer |  |  | $ 1,400,000 |  | $ 1,300,000 | $ 1,500,000
Percentage of contributions required for multiple collective-bargaining arrangements | 5.00% |  |  |  |  |
Other plans |  |  |  |  |  |
Multiemployer Plans [Line Items] |  |  |  |  |  |
Plan contributions | $ 1,108 | 1,106 |  | 1,463 |  |
Pension Plan |  |  |  |  |  |
Multiemployer Plans [Line Items] |  |  |  |  |  |
Multiemployer plans, surcharge | No |  |  |  |  |
Plan contributions | $ 3,103 | $ 3,017 | $ 272,300 | $ 3,856 | $ 257,800 | $ 290,100
Multiemployer plans, contributions by employer, percent | 5.00% |  |  |  |  |

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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
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- Definition Percentage of contributions required of employer under collective bargaining arrangement to total contributions required under all collective bargaining arrangements for pension and other postretirement plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
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