LONG-TERM DEBT (Schedule of Debt) (Details) - USD ($) $ in Millions	May. 31, 2015	May. 25, 2014	May. 26, 2013
Debt Instrument [Line Items]
Total face value of debt	$ 7,801.3	$ 8,736.8
Unamortized fair value adjustment of senior debt in connection with Ralcorp	146.7	154.5
Unamortized discounts/premiums	(32.8)	(46.5)
Unamortized debt issuance costs	(30.1)	(46.9)
Adjustment due to hedging activity	11.8	6.7
Less current installments	(1,008.0)	(84.1)
Total long-term debt	6,888.9	8,720.5
4.65% senior debt due January 2043
Debt Instrument [Line Items]
Total face value of debt	$ 737.0	$ 937.0	$ 1,000.0
Interest rate	4.65%	4.65%
6.625% senior debt due August 2039 (including Ralcorp senior notes)
Debt Instrument [Line Items]
Total face value of debt	$ 450.0	$ 450.0
Interest rate	6.625%	6.625%
8.25% senior debt due September 2030
Debt Instrument [Line Items]
Total face value of debt	$ 300.0	$ 300.0
Interest rate	8.25%	8.25%
7.0% senior debt due October 2028
Debt Instrument [Line Items]
Total face value of debt	$ 382.2	$ 382.2
Interest rate	7.00%	7.00%
6.7% senior debt due August 2027
Debt Instrument [Line Items]
Total face value of debt	$ 9.2	$ 9.2
Interest rate	6.70%	6.70%
7.125% senior debt due October 2026
Debt Instrument [Line Items]
Total face value of debt	$ 372.4	$ 372.4
Interest rate	7.125%	7.125%
3.2% senior debt due January 2023
Debt Instrument [Line Items]
Total face value of debt	$ 1,000.0	$ 1,225.0	$ 1,225.0
Interest rate	3.20%	3.20%
3.25% senior debt due September 2022
Debt Instrument [Line Items]
Total face value of debt	$ 250.0	$ 250.0
Interest rate	3.25%	3.25%
9.75% subordinated debt due March 2021
Debt Instrument [Line Items]
Total face value of debt	$ 195.9	$ 195.9
Interest rate	9.75%	9.75%
4.95% senior debt due August 2020 (including Ralcorp senior notes)
Debt Instrument [Line Items]
Total face value of debt	$ 300.0	$ 300.0
Interest rate	4.95%	4.95%
7.0% senior debt due April 2019
Debt Instrument [Line Items]
Total face value of debt	$ 475.0	$ 500.0
Interest rate	7.00%	7.00%
2.1% senior debt due March 2018
Debt Instrument [Line Items]
Total face value of debt	$ 225.0	$ 250.0
Interest rate	2.10%	2.10%
1.9% senior debt due January 2018
Debt Instrument [Line Items]
Total face value of debt	$ 1,000.0	$ 1,000.0
Interest rate	1.90%	1.90%
LIBOR plus 1.75% term loans due January 2018
Debt Instrument [Line Items]
Total face value of debt	$ 0.0	$ 900.0
Interest rate	1.75%	1.75%
5.819% senior debt due June 2017
Debt Instrument [Line Items]
Total face value of debt	$ 475.0	$ 500.0
Interest rate	5.819%	5.819%
LIBOR plus 0.37% term loans due July 2016
Debt Instrument [Line Items]
Total face value of debt	$ 550.0	$ 0.0
Interest rate	0.37%	0.37%
1.3% senior debt due January 2016
Debt Instrument [Line Items]
Total face value of debt	$ 750.0	$ 750.0
Interest rate	1.30%	1.30%
1.35% senior debt due September 2015
Debt Instrument [Line Items]
Total face value of debt	$ 250.0	$ 250.0
Interest rate	1.35%	1.35%
2.00% to 9.59% lease financing obligations due on various dates through 2040
Debt Instrument [Line Items]
Total face value of debt	$ 68.7	$ 78.7
2.00% to 9.59% lease financing obligations due on various dates through 2040 | Minimum
Debt Instrument [Line Items]
Interest rate	2.00%	2.00%
2.00% to 9.59% lease financing obligations due on various dates through 2040 | Maximum
Debt Instrument [Line Items]
Interest rate	9.59%	9.59%
Other indebtedness
Debt Instrument [Line Items]
Total face value of debt	$ 10.9	$ 86.4