Consolidated Statements of Comprehensive Loss - USD ($) $ in Millions	12 Months Ended
	Sep. 24, 2016	Sep. 26, 2015	Sep. 27, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 330.8	$ 131.6	$ 17.3
Changes in foreign currency translation adjustment, including amounts reclassified from AOCI	(10.4)	(11.0)	(13.3)
Other Comprehensive Income (Loss) available-for-sale securities adjustments including amounts reclassified from AOCI	(1.1)	(2.0)	(3.2)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	(6.1)	0.0	0.0
Changes in pension plans, net of taxes of $0.3 in 2016, $0.3 in 2015, and $0.2 in 2014	(0.7)	(0.2)	(1.3)
Changes in value of hedged interest rate caps, net of tax of $2.0 in 2016 and $2.5 in 2015:	3.4	3.9	0.0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	3.9	0.0	0.0
Other comprehensive loss	(17.8)	(17.1)	(17.8)
Comprehensive income (loss)	$ 313.0	$ 114.5	$ (0.5)