CPTC Loans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended
	Jun. 27, 2014	Sep. 30, 2011	Apr. 03, 2015	Sep. 26, 2014
Variable Interest Entity [Line Items]
Loan facility to CPTC		$ 165.3
CPTC loan facility, Varian's maximum loan commitment	80.3
Pro rata share of the Company's obligation to fund the initial distribution and subsequent advances	45.80%
Available-for-sale corporate debt securities			80.0	75.6
CPTC loan facility, interest rate margin	7.00%
CPTC loan facility, minimum interest rate	9.00%
CPTC loan facility, amortization period over which monthly payments are calculated after January 1, 2015	15 years
Accounts receivable from CPTC, includes unbilled accounts receivable			22.0	20.1
Tranche A loan
Variable Interest Entity [Line Items]
CPTC loan facility, Varian's maximum loan commitment	70.3	115.3	70.3
Pro rata share of the Company's obligation to fund the initial distribution and subsequent advances		69.75%
Tranche B loan
Variable Interest Entity [Line Items]
CPTC loan facility, Varian's maximum loan commitment	10.0		10.0
CPTC
Variable Interest Entity [Line Items]
Loan facility to CPTC	175.3
J.P. Morgan | Tranche A loan
Variable Interest Entity [Line Items]
Sale Of Portion Of Tranche A Loan Commitment	45.0
Sale of a portion of the outstanding Tranche A loan to JP Morgan chase Bank	38.1
Remaining obligation to fund Tranche A loan	6.9
Short-term Investments | Tranche A loan
Variable Interest Entity [Line Items]
Available-for-sale corporate debt securities			70.1	66.2
Other Assets | Tranche B loan
Variable Interest Entity [Line Items]
Available-for-sale corporate debt securities			$ 9.9	$ 9.4