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Employee Benefit Plans (Details) - USD ($)	12 Months Ended			240 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Related Party Transaction [Line Items]
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	$ 280,000	$ 275,000	$ 270,000
Employer Contribution Amount	4,200,000	4,100,000	$ 4,100,000
Separate Unrestricted Cash For Deferred Compensation Plans	36,700,000	28,200,000		$ 36,700,000
Deferred Compensation Liability	36,000,000.0	28,200,000		36,000,000.0
Officer [Member]
Related Party Transaction [Line Items]
Separate Unrestricted Cash For Deferred Compensation Plans	$ 36,000,000.0	$ 28,200,000		$ 36,000,000.0

X

- Definition

Separate Unrestricted Cash For Deferred Compensation Plan.

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

X

- 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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Balance Type:	credit
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X

- Definition

Amount of discretionary contributions made by an employer to a defined contribution plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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X

- 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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X

- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

+ Details

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X

- Definition

Maximum amount the employee may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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X

- 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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- Details

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