CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Millions	Total AAR Stockholders' Equity	Common Stock	Capital Surplus	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest	Total
Balance at May. 31, 2014	$ 999.5	$ 44.7	$ 436.4	$ 646.0	$ (98.3)	$ (29.3)	$ 1.2	$ 1,000.7
Increase (Decrease) in Stockholders' Equity
Net income	10.2			10.2			0.2	10.4
Cash dividends	(11.9)			(11.9)			(0.6)	(12.5)
Stock option activity	6.3		2.1		4.2			6.3
Restricted stock activity	4.2	0.2	4.7		(0.7)			4.2
Repurchase of shares	(151.5)				(151.5)			(151.5)
Other	(0.6)		(0.6)				$ (0.8)	(1.4)
Other comprehensive income (loss), net of tax	(11.1)					(11.1)		(11.1)
Balance at May. 31, 2015	845.1	44.9	442.6	644.3	(246.3)	(40.4)		845.1
Increase (Decrease) in Stockholders' Equity
Net income	47.7			47.7				47.7
Cash dividends	(10.4)			(10.4)				(10.4)
Stock option activity	6.7		4.4		2.3			6.7
Restricted stock activity	(0.3)		4.5		(4.8)			(0.3)
Repurchase of shares	(18.8)				(18.8)			(18.8)
Other	(0.2)		(0.2)					(0.2)
Other comprehensive income (loss), net of tax	(4.0)					(4.0)		(4.0)
Balance at May. 31, 2016	865.8	44.9	451.3	681.6	(267.6)	(44.4)		865.8
Increase (Decrease) in Stockholders' Equity
Net income	56.5			56.5				56.5
Cash dividends	(10.2)			(10.2)				(10.2)
Stock option activity	12.0		3.1		8.9			12.0
Restricted stock activity	5.4	0.3	6.4		(1.3)			5.4
Repurchase of shares	(19.8)				(19.8)			(19.8)
Other comprehensive income (loss), net of tax	4.5					4.5		4.5
Balance at May. 31, 2017	$ 914.2	$ 45.2	$ 460.8	$ 727.9	$ (279.8)	$ (39.9)		$ 914.2