Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended	13 Months Ended
	Apr. 30, 2016	Sep. 30, 2017	Sep. 30, 2017	Aug. 26, 2016	May 31, 2016
Derivative Litigation And James J. Cotter, Jr. Employment Arbitration [Member]
Commitments And Contingencies [Line Items]
Amount of damages claimed by plaintiff		$ 1.2	$ 1.2
Coverage limit		10.0
The STOMP Arbitration [Member]
Commitments And Contingencies [Line Items]
Settlement awarded	$ 2.3
Litigation interest percent	4.00%
Litigation payment received		$ 1.1	$ 1.6
Litigation final payment date		June 2019
Class B [Member] | Derivative Litigation And James J. Cotter, Jr. Employment Arbitration [Member]
Commitments And Contingencies [Line Items]
Shares held by estate				100,000
Class B [Member] | Cotter Estate [Member] | Derivative Litigation And James J. Cotter, Jr. Employment Arbitration [Member]
Commitments And Contingencies [Line Items]
Shares held by estate					327,808
Class B [Member] | Cotter Trust [Member] | Derivative Litigation And James J. Cotter, Jr. Employment Arbitration [Member]
Commitments And Contingencies [Line Items]
Shares held by estate					696,080