Commitments And Contingencies (Narrative) (Details) - USD ($)		1 Months Ended	9 Months Ended		12 Months Ended
	Oct. 01, 2018	Apr. 30, 2016	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	May 31, 2016
Cotter, Jr. Related Litigation Matters [Member]
Commitments And Contingencies [Line Items]
Amount of damages claimed by plaintiff			$ 1,000,000
Litigation expense			3,100,000	$ 1,100,000	$ 4,000,000
Coverage limit			$ 10,000,000
The STOMP Arbitration [Member]
Commitments And Contingencies [Line Items]
Settlement awarded		$ 2,300,000
Subsequent Event [Member] | Cotter, Jr. Related Litigation Matters [Member]
Commitments And Contingencies [Line Items]
Incurred expenses exceeding insurance limit	$ 1,500,000
Class B [Member] | Cotter Estate [Member] | Cotter, Jr. Related Litigation Matters [Member]
Commitments And Contingencies [Line Items]
Shares held by estate			427,808			327,808
Class B [Member] | Cotter Estate [Member] | Cotter, Jr. Related Litigation Matters [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Additional voting stock that may be awarded			25.50%
Class B [Member] | Cotter Trust [Member] | Cotter, Jr. Related Litigation Matters [Member]
Commitments And Contingencies [Line Items]
Shares held by estate			696,080			696,080
Voting stock percent			41.40%
Class B [Member] | Cotter Voting Trust [Member] | Cotter, Jr. Related Litigation Matters [Member]
Commitments And Contingencies [Line Items]
Voting stock percent			66.90%