CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 30, 2018	Mar. 31, 2017	Mar. 30, 2018	Mar. 31, 2017	Sep. 29, 2017
Statement of Cash Flows [Abstract]
Net (loss) earnings	$ 73.2	$ 56.2	$ (39.0)	$ 70.7
Adjustments to reconcile net earnings to net cash provided by operating activities:
Share-based compensation expense			21.2	23.6
Depreciation			25.4	31.9
Amortization of intangible assets			10.4	9.1
Deferred taxes			41.8	(7.5)
Loss on hedges related to the Sirtex acquisition			16.4	0.0
Provision for doubtful accounts receivable			2.0	38.8
Impairment charges	11.1	0.0	11.1	38.3
Other, net			0.0	(0.7)
Changes in assets and liabilities:
Trade and unbilled receivables			28.4	(14.5)
Inventories			(10.9)	(14.3)
Prepaid expenses and other assets			0.0	(55.5)
Accounts payable			0.9	(9.9)
Accrued liabilities and other long-term liabilities			125.3	(25.5)
Deferred revenues			11.5	29.9
Net cash provided by operating activities			244.5	114.4
Cash flows from investing activities:
Purchases of property, plant and equipment			(17.8)	(32.1)
Acquisitions, net of cash acquired			(29.6)	0.0
Issuance of notes receivable			0.0	(11.5)
Principal payments on notes receivable			5.2	0.0
Investment in available-for-sale securities			(6.0)	(1.1)
Sale of available-for-sale securities			8.0	0.0
Loans to CPTC			(5.3)	0.0
Purchase of foreign currency option related to the Sirtex acquisition			(5.5)	0.0
Investment in privately-held companies			(3.1)	(5.0)
Amounts paid to deferred compensation plan trust account			(1.3)	(4.4)
Other, net			0.3	0.9
Net cash used in investing activities			(55.1)	(53.2)
Cash flows from financing activities:
Repurchases of common stock			(92.7)	(222.3)
Proceeds from issuance of common stock to employees			44.6	25.4
Employees' taxes withheld and paid for restricted stock and restricted stock units			(11.1)	(10.5)
Cash received from Varex Imaging Corporation			0.0	200.0
Cash and cash equivalents contributed to Varex Imaging Corporation			0.0	(81.3)
Borrowings under credit facility agreement			234.3	90.0
Repayments under credit facility agreement			(209.3)	(100.0)
Net repayments under the credit facility agreements with maturities less than 90 days			(120.0)	(107.0)
Other			0.0	0.7
Net cash used in financing activities			(154.2)	(205.0)
Effects of exchange rate changes on cash and cash equivalents			(11.5)	7.3
Net increase (decrease) in cash and cash equivalents			23.7	(136.5)
Cash and cash equivalents at beginning of period			716.2	843.5	$ 843.5
Cash and cash equivalents at end of period	$ 739.9	$ 707.0	$ 739.9	$ 707.0	$ 716.2