Fair Value Measurements Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013	Dec. 29, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 3.0		$ 3.0		$ 2.9
Available-for-sale investment	98.0		98.0		80.7
Total assets at fair value	101.0		101.0		83.6
Other comprehensive income (loss), Unrealized gains and losses on Investment	10.6	11.5	10.5	23.8
Available-for-sale Equity Securities, Amortized Cost Basis	20.4		20.4		19.7
Asset impairments	0	1.7	0	1.7
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	3.0		3.0		2.9
Available-for-sale investment	98.0		98.0		80.7
Total assets at fair value	101.0		101.0		83.6
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0		0		0
Available-for-sale investment	0		0		0
Total assets at fair value	0		0		0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0		0		0
Available-for-sale investment	0		0		0
Total assets at fair value	0		0		0
Temp Holdings Investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other comprehensive income (loss), Unrealized gains and losses on Investment	$ 10.6	$ 11.5	$ 10.5	$ 23.8