3. Fair Value Measurements Fair Value Level Table (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
		Jun. 30, 2020	Jun. 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		$ 1,183.5	$ 2,011.2
Debt Securities, Available-for-sale		$ 375.5	$ 375.5
Business Combination, Contingent Consideration, Liability				$ 0.1			$ 0.6
Investment ownership percentage		37.00%	37.00%
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]	6,724.1	6,724.1		4,664.4
Debt Securities, Available-for-sale	[3]	375.5	375.5		402.9
Forward Foreign Exchange Contracts, Asset, Fair Value Disclosure	[4]	0.6	0.6		0.9
Assets, Fair Value Disclosure		7,327.7	7,327.7		5,227.9
Forward Foreign Exchange Contracts, Liability, Fair Value Disclosure	[5]	0.2	0.2		1.0
Business Combination, Contingent Consideration, Liability	[6]	2.7	2.7		4.9
Liabilities, Fair Value Disclosure		2.9	2.9		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]	6,724.1	6,724.1		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		6,873.1	6,873.1		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		375.5	375.5		402.9	[3]
Forward Foreign Exchange Contracts, Asset, Fair Value Disclosure	[4]	0.6	0.6		0.9
Assets, Fair Value Disclosure		454.6	454.6		456.8
Forward Foreign Exchange Contracts, Liability, Fair Value Disclosure	[5]	0.2	0.2		1.0
Business Combination, Contingent Consideration, Liability	[6]	0.0	0.0		0.0
Liabilities, Fair Value Disclosure		0.2	0.2		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]	2.7	2.7		4.9
Liabilities, Fair Value Disclosure		2.7	2.7		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]	67.7	67.7		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]	67.7	67.7		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]	36.5	36.5		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]	26.5	26.5		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]	115.9	115.9		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]	115.9	115.9		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]	220.9	220.9		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]	142.4	142.4		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]	78.5	78.5		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		0.7	0.7
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		0.7	0.7
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	[3]	2.1	2.1
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	[3]	0.0	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	[3]	2.1	2.1
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	[3]	0.0	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]	14.8	14.8		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]	14.8	14.8		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]	5.6	5.6		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]	5.6	5.6		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]	173.9	173.9		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]	173.9	173.9		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]	118.0	118.0		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]	118.0	118.0		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]	61.1	61.1		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]	61.1	61.1		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]	2.6	2.6		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]	49.0	49.0		51.0
Debt Securities, Available-for-sale	[3]	375.4	375.4		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		14.8	14.8		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		5.6	5.6		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		173.9	173.9		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		118.0	118.0		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		61.0	61.0		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]	6,675.1	6,675.1		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		2.0	2.0
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): June 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): June 30, 2020December 31, 2019Short-term investments$49.0  $51.0  Other investments6,675.1  4,613.4          Total$6,724.1  $4,664.4  

[3] Available-for-sale investments are included in the following accounts in the condensed consolidated balance sheets (in millions):  June 30, 2020December 31, 2019Short-term investments$375.4  $402.8  Other investments0.1  0.1  Total$375.5  $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): June 30, 2020December 31, 2019Other current liabilities$2.6  $3.3  Other long-term liabilities0.1  1.6     Total$2.7  $4.9  

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