Investments - Other Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summarized financial information of unconsolidated entities
Total assets, unconsolidated entities	$ 135,355.6	$ 136,171.8
Total liabilities, unconsolidated entities	80,265.4	83,815.2
Total equity, unconsolidated entities	55,090.2	52,356.6
Net investment in unconsolidated entities	1,723.7	1,616.2
Total revenues, unconsolidated entities	15,389.4	15,020.9	$ 14,376.4
Net income, unconsolidated entities	6,542.1	4,530.1	3,455.3
Our share of net income of unconsolidated entities	161.6	232.7	$ 232.7
Other Types of Investments
Direct financing leases	830.7	937.4
Company owned life insurance	502.6	0.0
Certain sponsored investment funds	$ 719.7	$ 396.4