Equity - Activity for Class B Common Stock and Treasury Stock (Details) - shares	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Class B Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Purchase of Treasury Stock			100,000
Common Stock \| Class B Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	101,240,873	101,436,577	100,803,382	101,100,453
Stock Award Activity	22,750	41,450	521,074	496,219
Purchase of Treasury Stock	52,600	714,865	113,433	833,510
Ending Balance	101,211,023	100,763,162	101,211,023	100,763,162
Treasury Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(8,264,583)	(8,068,879)	(8,702,074)	(8,405,003)
Stock Award Activity	22,750	41,450	521,074	496,219
Purchase of Treasury Stock	52,600	714,865	113,433	833,510
Ending Balance	(8,294,433)	(8,742,294)	(8,294,433)	(8,742,294)

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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- Definition

Number of shares that have been repurchased during the period and are being held in treasury.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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