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Employee Benefit Plans (Details) | 12 Months Ended | 192 Months Ended | 216 Months Ended
--- | --- | --- | ---
Dec. 31, 2017 USD ($) mo | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2016 USD ($) yr age | Dec. 31, 2017 USD ($)
Employee Benefit Plans [Abstract] |  |  |  |  |
Eligibility Period For 401K Savings Plan In Months | mo | 3 |  |  |  |
Employer Matching Contribution, Percent of Match |  |  |  |  | 200.00%
Employer Matching Contribution, Percent of Employees' Gross Pay |  |  |  |  | 3.00%
Maximum Eligible Earnings As Established By IRS For Matching Contributions | $ 270,000 | $ 265,000 | $ 265,000 |  |
Employer Contribution Amount | 4,100,000 | 4,000,000 | 3,700,000 |  |
Years Of Service For Supplemental Retirement Contribution | yr |  |  |  | 10 |
Age Of Employee For Supplemental Retirement Contribution | age |  |  |  | 40 |
Annual Supplemental Retirement Contribution And Credit Total. | 18,000 | 21,000 | $ 42,000 |  |
Separate Unrestricted Cash For Deferred Compensation Plan. | 29,200,000 | 23,800,000 |  | $ 23,800,000 | $ 29,200,000
Deferred Compensation Liability | $ 29,200,000 | $ 23,800,000 |  | $ 23,800,000 | $ 29,200,000

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- Definition Maximum Eligible Earnings As Established By IRS For Matching Contributions + References No definition available. + Details
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- Definition Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date. + References No definition available. + 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 employer matches of the employee's percentage contribution matched. + References No definition available. + Details
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