Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions		6 Months Ended
	Jun. 03, 2016	Jun. 30, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment from adoption of ASU 2016-09			$ 39.0
Baxalta
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fair value of purchase consideration	$ 32,393.7	$ 32,393.7
Additional paid-in capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment from adoption of ASU 2016-09			10.7
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment from adoption of ASU 2016-09			28.3
Accounting Standards Update 2016-09, Excess Tax Benefit Component | Additional paid-in capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment from adoption of ASU 2016-09			11.5
Accounting Standards Update 2016-09, Excess Tax Benefit Component | Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment from adoption of ASU 2016-09			39.0
Accounting Standards Update 2016-09, Forfeiture Rate Component | Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment from adoption of ASU 2016-09			$ 10.7