Accounting Changes and Recent Accounting Pronouncements (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting standards update	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201602Member
Stockholders equity cumulative effect adjustment		$ 13,198.6	$ 4,148.3	$ 12,765.0	$ 12,550.5	$ 12,912.2	$ 13,361.6	$ 3,670.7	$ 3,849.6
Accumulated earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders equity cumulative effect adjustment		$ 6,350.4	$ (5,172.2)	$ 5,722.6	$ 6,745.7	$ 7,269.9	$ 7,736.9	$ (5,111.0)	$ (5,164.0)