Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2016	Feb. 22, 2015	Feb. 28, 2016	Feb. 22, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss), pre-tax amount	$ 318.2	$ (949.3)	$ (973.1)	$ (68.1)
Net income (loss), tax (expense) benefit	(111.9)	(3.4)	186.3	(384.2)
Net income (loss)	206.3	(952.7)	(786.8)	(452.3)
Derivative adjustments:
Unrealized derivative adjustments, pre-tax amount	0.0	0.0	0.0	0.0
Unrealized derivative adjustments, tax (expense) benefit	0.0	0.0	0.0	0.0
Unrealized derivative adjustments, after-tax amount	0.0	0.0	0.0	0.0
Reclassification for derivative adjustments included in net income, pre-tax amount	(2.1)	0.0	(2.1)	(0.5)
Reclassification for derivative adjustments included in net income, tax (expense) benefit	0.8	0.0	0.8	0.2
Reclassification for derivative adjustments included in net income, after-tax amount	(1.3)	0.0	(1.3)	(0.3)
Unrealized gains on available-for-sale securities, pre-tax amount	(0.1)	0.4	0.0	0.7
Unrealized gains on available-for-sale securities, tax (expense) benefit	0.0	(0.2)	0.0	(0.3)
Unrealized gains on available-for-sale securities, after-tax amount	(0.1)	0.2	0.0	0.4
Currency translation losses:
Unrealized currency translation losses, pre-tax amount	(18.0)	(82.8)	(74.0)	(135.6)
Unrealized currency translation losses, tax (expense) benefit	0.0	0.0	0.0	0.0
Unrealized currency translation losses, after-tax amount	(18.0)	(82.8)	(74.0)	(135.6)
Reclassification for currency translation losses included in net income, pre-tax amount	73.4	0.0	73.4	0.0
Reclassification for currency translation losses included in net income, tax (expense) benefit	0.0	0.0	0.0	0.0
Reclassification for currency translation losses included in net income, after-tax amount	73.4	0.0	73.4	0.0
Pension and post-employment benefit obligations:
Unrealized pension and post-employment benefit obligations, pre-tax amount	0.4	0.0	7.1	3.8
Unrealized pension and post-employment benefit obligations, tax (expense) benefit	(0.1)	0.0	(1.8)	(0.9)
Unrealized pension and post-employment benefit obligations, after-tax amount	0.3	0.0	5.3	2.9
Reclassification for pension and post-employment benefit obligations included in net income, pre-tax amount	(10.9)	(0.2)	(13.5)	(0.6)
Reclassification for pension and post-employment benefit obligations included in net income, tax (expense) benefit	3.4	0.1	4.4	0.2
Reclassification for pension and post-employment benefit obligations included in net income, after-tax amount	(7.5)	(0.1)	(9.1)	(0.4)
Comprehensive income (loss), pre-tax amount	360.9	(1,031.9)	(982.2)	(200.3)
Comprehensive income (loss), tax (expense) benefit	(107.8)	(3.5)	189.7	(385.0)
Comprehensive income (loss), after-tax amount	253.1	(1,035.4)	(792.5)	(585.3)
Comprehensive income (loss) attributable to noncontrolling interests, pre-tax amount	(0.3)	0.8	2.3	4.1
Comprehensive income (loss) attributable to noncontrolling interested, tax (expense) benefit	(0.2)	(0.2)	(0.7)	(0.2)
Comprehensive income (loss) attributable to noncontrolling interests, after-tax amount	(0.5)	0.6	1.6	3.9
Comprehensive income (loss) attributable to ConAgra Foods, Inc., pre-tax amount	361.2	(1,032.7)	(984.5)	(204.4)
Comprehensive income (loss) attributable to ConAgra Foods, Inc., tax (expense) benefit	(107.6)	(3.3)	190.4	(384.8)
Comprehensive income (loss) attributable to ConAgra Foods, Inc., after-tax amount	$ 253.6	$ (1,036.0)	$ (794.1)	$ (589.2)