Leases (Schedule of Cumulative Effects of Adoption of ASC 842) (Details) (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Preferred Stock, par value per share	$ 5.00	$ 5.00
Preferred Stock, shares authorized	2,000,000	2,000,000
Preferred Stock, shares issued	0	0
Treasury stock, shares	8,408,770	8,418,620
Common Class A [Member]
Common Stock, par value per share	$ 1	$ 1
Common Stock, shares authorized	100,000,000	100,000,000
Common Stock, shares issued	39,098,292	37,450,329
Common Class B [Member]
Common Stock, par value per share	$ 1	$ 1
Common Stock, shares authorized	25,000,000	25,000,000
Common Stock, shares issued	1,617,998	3,233,998
Common Stock, shares outstanding	1,617,998	3,233,998
As previously reported [Member]
Preferred Stock, par value per share		$ 5.00
Preferred Stock, shares authorized		2,000,000
Preferred Stock, shares issued		0
As previously reported [Member] | Common Class A [Member]
Common Stock, par value per share		$ 1	$ 1
Common Stock, shares authorized		100,000,000	100,000,000
Common Stock, shares issued		37,450,329	37,395,753
Treasury stock, shares		8,418,620	8,431,335
As previously reported [Member] | Common Class B [Member]
Common Stock, par value per share		$ 1	$ 1
Common Stock, shares authorized		25,000,000	25,000,000
Common Stock, shares issued		3,233,998	3,233,998
Common Stock, shares outstanding		3,233,998	3,233,998
Adjustments Increase/(Decrease) [Member]
Preferred Stock, par value per share		$ 5.00
Preferred Stock, shares authorized		2,000,000
Preferred Stock, shares issued		0
Adjustments Increase/(Decrease) [Member] | Common Class A [Member]
Common Stock, par value per share		$ 1	$ 1
Common Stock, shares authorized		100,000,000	100,000,000
Common Stock, shares issued		37,450,329	37,395,753
Adjustments Increase/(Decrease) [Member] | Common Class B [Member]
Common Stock, par value per share		$ 1	$ 1
Common Stock, shares authorized		25,000,000	25,000,000
Common Stock, shares issued		3,233,998	3,233,998
Common Stock, shares outstanding		3,233,998	3,233,998
Opening balance, as adjusted, January 1, 2019 [Member]
Preferred Stock, par value per share		$ 5.00
Preferred Stock, shares authorized		2,000,000
Preferred Stock, shares issued		0
Opening balance, as adjusted, January 1, 2019 [Member] | Common Class A [Member]
Common Stock, par value per share		$ 1	$ 1
Common Stock, shares authorized		100,000,000	100,000,000
Common Stock, shares issued		37,450,329	37,395,753
Opening balance, as adjusted, January 1, 2019 [Member] | Common Class B [Member]
Common Stock, par value per share		$ 1	$ 1
Common Stock, shares authorized		25,000,000	25,000,000
Common Stock, shares issued		3,233,998	3,233,998
Common Stock, shares outstanding		3,233,998	3,233,998