Income Taxes (Income Tax Benefit (Provision) (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Aug. 31, 2018	Feb. 28, 2018	Aug. 31, 2017	Aug. 31, 2018	Aug. 31, 2017
Income Tax Disclosure [Abstract]
Write down of deferred tax asset resulting from Tax Cuts and Jobs Act			$ 68,600
Benefit (provision) for income taxes	[1]	$ 98,298		$ 124,795	$ 306,870	$ 253,656
Effective tax rate		17.80%		33.40%	25.40%	33.60%
Income tax benefit from tax accounting method changes and energy credits		$ 34,100
Effective income tax rate excluding impact of Tax Cuts and Jobs Act, Accounting Method Changes, and Energy Credits					22.60%

[1] Provision for income taxes for the nine months ended August 31, 2018 includes a non-cash one-time write down of deferred tax assets of $68.6 million resulting from the Tax Cuts and Jobs Act enacted in December 2017.