3. Fair Value Measurements Fair Value Level Table (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020		Sep. 30, 2020		Apr. 01, 2020	Dec. 31, 2019		Oct. 01, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Gain on Securities		$ 1,580.3		$ 3,591.5
Debt Securities, Available-for-sale		261.3		261.3
Business Combination, Contingent Consideration, Liability						$ 0.1			$ 0.6
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted Investments, at Fair Value	[1]	6.6		6.6			$ 5.6
Equity Securities	[2]	8,459.3		8,459.3			4,664.4
Debt Securities, Available-for-sale	[3]	261.3		261.3			402.9
Forward Foreign Exchange Contracts, Asset, Fair Value Disclosure	[4]	0.6		0.6			0.9
Assets, Fair Value Disclosure		9,060.0		9,060.0			5,227.9
Forward Foreign Exchange Contracts, Liability, Fair Value Disclosure	[5]	1.3		1.3			1.0
Business Combination, Contingent Consideration, Liability	[6]	2.3		2.3			4.9
Liabilities, Fair Value Disclosure		3.6		3.6			5.9
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted Investments, at Fair Value	[1]	6.6		6.6			5.6
Equity Securities	[2]	8,459.3		8,459.3			4,664.4
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
Forward Foreign Exchange Contracts, Asset, Fair Value Disclosure	[4]	0.0		0.0			0.0
Assets, Fair Value Disclosure		8,607.6		8,607.6			4,771.1
Forward Foreign Exchange Contracts, Liability, Fair Value Disclosure	[5]	0.0		0.0			0.0
Business Combination, Contingent Consideration, Liability	[6]	0.0		0.0			0.0
Liabilities, Fair Value Disclosure		0.0		0.0			0.0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted Investments, at Fair Value	[1]	0.0		0.0			0.0
Equity Securities	[2]	0.0		0.0			0.0
Debt Securities, Available-for-sale		261.3		261.3			402.9	[3]
Forward Foreign Exchange Contracts, Asset, Fair Value Disclosure	[4]	0.6		0.6			0.9
Assets, Fair Value Disclosure		452.4		452.4			456.8
Forward Foreign Exchange Contracts, Liability, Fair Value Disclosure	[5]	1.3		1.3			1.0
Business Combination, Contingent Consideration, Liability	[6]	0.0		0.0			0.0
Liabilities, Fair Value Disclosure		1.3		1.3			1.0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted Investments, at Fair Value	[1]	0.0		0.0			0.0
Equity Securities	[2]	0.0		0.0			0.0
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
Forward Foreign Exchange Contracts, Asset, Fair Value Disclosure	[4]	0.0		0.0			0.0
Assets, Fair Value Disclosure		0.0		0.0			0.0
Forward Foreign Exchange Contracts, Liability, Fair Value Disclosure	[5]	0.0		0.0			0.0
Business Combination, Contingent Consideration, Liability	[6]	2.3		2.3			4.9
Liabilities, Fair Value Disclosure		2.3		2.3			4.9
US Government Sponsored Agencies [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		0.0		0.0
Asset-backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0.1		0.1			0.1
Asset-backed Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0.0		0.0			0.0
Asset-backed Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0.1		0.1			0.1
Asset-backed Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0.0		0.0			0.0
Commercial Paper [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	108.8		108.8			42.9
Commercial Paper [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0.0		0.0			0.0
Commercial Paper [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	108.8		108.8			42.9
Commercial Paper [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0.0		0.0			0.0
Time Deposits [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	24.6		24.6			41.2
Time Deposits [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	14.6		14.6			31.2
Time Deposits [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	10.0		10.0			10.0
Time Deposits [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0.0		0.0			0.0
Money Market Funds [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	127.1		127.1			69.9
Money Market Funds [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	127.1		127.1			69.9
Money Market Funds [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0.0		0.0			0.0
Money Market Funds [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0.0		0.0			0.0
Cash Equivalents [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	332.2		332.2			154.1
Cash Equivalents [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	141.7		141.7			101.1
Cash Equivalents [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	190.5		190.5			53.0
Cash Equivalents [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0.0		0.0			0.0
US Treasury Securities | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		71.6		71.6
US Treasury Securities | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		71.6		71.6
US Treasury Securities | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		0.0		0.0
Foreign Government Debt [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		2.1	[3]	2.1	[3]		3.1
Foreign Government Debt [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		0.0	[3]	0.0	[3]		0.0
Foreign Government Debt [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		2.1	[3]	2.1	[3]		3.1
Foreign Government Debt [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		0.0	[3]	0.0	[3]		0.0
Municipal Obligations (Member) | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	13.4		13.4			11.6
Municipal Obligations (Member) | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
Municipal Obligations (Member) | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	13.4		13.4			11.6
Municipal Obligations (Member) | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
Foreign Government Obligations [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	5.0		5.0			4.7
Foreign Government Obligations [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
Foreign Government Obligations [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	5.0		5.0			4.7
Foreign Government Obligations [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
Corporate Debt Securities [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	114.4		114.4			204.5
Corporate Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
Corporate Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	114.4		114.4			204.5
Corporate Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
US Government Sponsored Agencies [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	78.2		78.2			106.1
US Government Sponsored Agencies [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
US Government Sponsored Agencies [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	78.2		78.2			106.1
US Government Sponsored Agencies [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
Asset-backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	48.2		48.2			72.9
Asset-backed Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
Asset-backed Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	48.2		48.2			72.9
Asset-backed Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	[3]	0.0		0.0			0.0
Other Current Liabilities [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[6]	2.2		2.2			3.3
Other Noncurrent Liabilities [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[6]	0.1		0.1			1.6
Short-term Investments [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities	[2]	53.0		53.0			51.0
Debt Securities, Available-for-sale	[3]	261.2		261.2			402.8
Short-term Investments [Member] | Foreign Government Debt [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		2.1		2.1			3.1
Short-term Investments [Member] | Municipal Obligations (Member) | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		13.4		13.4			11.6
Short-term Investments [Member] | Foreign Government Obligations [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		5.0		5.0			4.7
Short-term Investments [Member] | Corporate Debt Securities [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		114.4		114.4			204.5
Short-term Investments [Member] | US Government Sponsored Agencies [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		78.2		78.2			106.1
Short-term Investments [Member] | Asset-backed Securities [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		48.1		48.1			72.8
Other Investments [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted Investments, at Fair Value		1.0		1.0			0.0
Equity Securities	[2]	8,406.3		8,406.3			4,613.4
Debt Securities, Available-for-sale	[3]	0.1		0.1			0.1
Restricted investment [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted Investments, at Fair Value		5.6		5.6			$ 5.6
Analytical Flow Cytometer Platform [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability		1.6		1.6
Sales milestone minimum amount [Member] | Analytical Flow Cytometer Platform [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low		$ 0.0		$ 0.0

[1] Restricted investments are included in the following accounts in the condensed consolidated balance sheets (in millions): September 30, 2020December 31, 2019Restricted investments$5.6 $5.6 Other investments1.0 —     Total$6.6 $5.6 

[2] Equity securities are included in the following accounts in the condensed consolidated balance sheets (in millions): September 30, 2020December 31, 2019Short-term investments$53.0 $51.0 Other investments8,406.3 4,613.4         Total$8,459.3 $4,664.4 

[3] Available-for-sale investments are included in the following accounts in the condensed consolidated balance sheets (in millions):  September 30, 2020December 31, 2019Short-term investments$261.2 $402.8 Other investments0.1 0.1 Total$261.3 $402.9 

[4] Forward foreign exchange contracts in an asset position are included in Other current assets in the condensed consolidated balance sheets.

[5] Forward foreign exchange contracts in a liability position are included in Other current liabilities in the condensed consolidated balance sheets.

[6] Contingent consideration liability is included in the following accounts in the condensed consolidated balance sheets (in millions): September 30, 2020December 31, 2019Other current liabilities$2.2 $3.3 Other long-term liabilities0.1 1.6    Total$2.3 $4.9 

[7] Cash equivalents are included in Cash and cash equivalents in the condensed consolidated balance sheets.