Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
May 31, 2018	May 31, 2017	May 31, 2018	May 31, 2017
Statement of Comprehensive Income [Abstract]
Amortization of interest rate swap, net of tax benefit	$ 71	$ 103	$ 152	$ 207

Other Comprehensive Income, Amortization Adjustments on Derivatives, Included in Net Income, Tax

No definition available.

Name:	isca_OtherComprehensiveIncomeAmortizationAdjustmentsOnDerivativesIncludedInNetIncomeTax
Namespace Prefix:	isca_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration