Caelum Biosciences - Carrying Value (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Noncontrolling Interest [Line Items]
Cash and cash equivalents	$ 3,429.6	$ 2,964.5	$ 2,315.0
Prepaid expenses and other current assets	706.4	648.6
Other assets	447.0	506.2
Accounts payable	125.3	118.6
Accrued expenses	910.7	$ 1,084.7
Variable Interest Entity, Primary Beneficiary
Noncontrolling Interest [Line Items]
Cash and cash equivalents	56.5
Prepaid expenses and other current assets	8.6
Other assets	7.8
Accounts payable	3.6
Accrued expenses	$ 2.3