Supplemental Guarantor Information - Condensed Consolidating Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Condensed Consolidating Financial Statements
Net income	$ 842,586	$ 480,708	$ 693,520
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	19,276	(10,252)	(11,933)
Cumulative translation adjustment on Shred-it	0	0	6,472
Change in fair value of cash flow hedges	0	31,136	(12,156)
Amortization of interest rate lock agreements	(933)	1,076	1,952
Other	1,029	(115)	(738)
Other comprehensive income (loss), net of tax expense (benefit) of $690, $19,118 and ($9,813), respectively	19,372	21,845	(16,403)
Comprehensive income (loss)	861,958	502,553	677,117
Eliminations
Condensed Consolidating Financial Statements
Net income	(840,634)	(477,624)	(700,704)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(19,276)	10,252	0
Cumulative translation adjustment on Shred-it			0
Change in fair value of cash flow hedges		(31,136)	0
Amortization of interest rate lock agreements	933	(1,076)	0
Other	(1,029)	115	0
Other comprehensive income (loss), net of tax expense (benefit) of $690, $19,118 and ($9,813), respectively	(19,372)	(21,845)	0
Comprehensive income (loss)	(860,006)	(499,469)	(700,704)
Cintas Corporation | Corporate
Condensed Consolidating Financial Statements
Net income	842,586	480,708	693,520
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	19,276	(10,252)	0
Cumulative translation adjustment on Shred-it			0
Change in fair value of cash flow hedges		31,136	0
Amortization of interest rate lock agreements	(933)	1,076	0
Other	1,029	(115)	0
Other comprehensive income (loss), net of tax expense (benefit) of $690, $19,118 and ($9,813), respectively	19,372	21,845	0
Comprehensive income (loss)	861,958	502,553	693,520
Corp. 2 | Corporate
Condensed Consolidating Financial Statements
Net income	342,851	152,916	400,191
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	0	0	0
Cumulative translation adjustment on Shred-it			5,875
Change in fair value of cash flow hedges		31,136	(12,156)
Amortization of interest rate lock agreements	(933)	1,076	1,952
Other	267	0	0
Other comprehensive income (loss), net of tax expense (benefit) of $690, $19,118 and ($9,813), respectively	(666)	32,212	(4,329)
Comprehensive income (loss)	342,185	185,128	395,862
Subsidiary Guarantors | Corporate
Condensed Consolidating Financial Statements
Net income	470,215	315,565	296,608
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	0	0	0
Cumulative translation adjustment on Shred-it			0
Change in fair value of cash flow hedges		0	0
Amortization of interest rate lock agreements	0	0	0
Other	762	(115)	(730)
Other comprehensive income (loss), net of tax expense (benefit) of $690, $19,118 and ($9,813), respectively	762	(115)	(730)
Comprehensive income (loss)	470,977	315,450	295,878
Non- Guarantors | Corporate
Condensed Consolidating Financial Statements
Net income	27,568	9,143	3,905
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	19,276	(10,252)	(11,933)
Cumulative translation adjustment on Shred-it			597
Change in fair value of cash flow hedges		0	0
Amortization of interest rate lock agreements	0	0	0
Other	0	0	(8)
Other comprehensive income (loss), net of tax expense (benefit) of $690, $19,118 and ($9,813), respectively	19,276	(10,252)	(11,344)
Comprehensive income (loss)	$ 46,844	$ (1,109)	$ (7,439)