Accumulated Other Comprehensive Income (Loss) - Schedule of Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2018	May 31, 2017	May 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									$ 110,175	$ 86,524	$ 64,522
Tax (expense) benefit									(57,069)	(230,118)	(256,710)
Amortization of interest rate locks, net of tax	$ 189,298	$ 295,789	$ 137,737	$ 161,108	$ 82,174	$ 116,954	$ 121,950	$ 136,208	783,932	457,286	$ 448,605
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax (expense) benefit									(571)	638
Amortization of interest rate locks, net of tax									933	(1,076)
Interest Rate Contract | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									$ 1,504	$ (1,714)