Fair Value Measurements Narrative (Details 3) - USD ($)	6 Months Ended	12 Months Ended
	Dec. 31, 2015	Jun. 27, 2015	Jun. 28, 2014	Nov. 08, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets, Level 1, Level 2, Level 3 Transfers, Amount	$ 0	$ 0	$ 0
Senior Notes	4,698,300,000	4,720,900,000	2,300,000,000	$ 2,300,000,000
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of fixed-rate long-term debt		3,900,000,000
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of fixed-rate long-term debt			$ 2,400,000,000
Public Bonds and Private Placement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes	3,900,000,000	3,900,000,000
Public Bonds and Private Placement [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of fixed-rate long-term debt	3,800,000,000
Retail Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt	798,300,000	820,900,000
Debt Instrument, Unamortized Premium	82,500,000	97,100,000
Retail Bonds [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of fixed-rate long-term debt	$ 859,800,000	$ 902,400,000