Comprehensive Income - Components of accumulated other comprehensive loss, net of taxes (Details) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2013	Aug. 31, 2012
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Pension and other postretirement, net of tax benefit of $(145,031) and $(123,321) in 2012 and 2011 in 2012 and 2011, respectively	$ (165,611)	$ (228,727)
Unrealized net gain on available for sale investments, net of tax expense of $858 and $659 in 2012 and 2011, respectively	2,370	1,391
Treasury locks and swaps, net of tax benefit of $(2,347) and $(2,796) in 2012 and 2011	11,685	(3,806)
Foreign currency translation adjustment, net of tax expense (benefit) of $(891) and $2,808 in 2012 and 2011, respectively	(5,311)	(1,445)
Accumulated other comprehensive loss, including noncontrolling interests	(156,867)	(232,587)
Accumulated other comprehensive loss attributable to noncontrolling interests
Accumulated other comprehensive loss attributable to parent	(156,867)	(232,587)
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Pension and other postretirement, tax	(145,031)	(123,321)
Unrealized net gain (loss) on available for sale investments, tax	858	659
Accumulated Other Comprehensive Income, Including Portion Attributable to Noncontrolling Interest, Treasury Locks and Swaps, Tax	(2,347)	(2,796)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	$ (891)	$ 2,808