Debt Obligations, Debt Maturities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Scheduled Maturities of Debt [Abstract]
2019	$ 1,500.0
2020	1,500.0
2021	1,325.0
2022	1,400.0
2023	1,250.0
Thereafter	19,445.6
Total	26,420.6	$ 24,780.1
Senior Notes [Member]
Scheduled Maturities of Debt [Abstract]
2019	1,500.0
2020	1,500.0
2021	1,325.0
2022	1,400.0
2023	1,250.0
Thereafter	16,775.0
Total	23,750.0
Junior Subordinated Notes [Member]
Scheduled Maturities of Debt [Abstract]
2019	0.0
2020	0.0
2021	0.0
2022	0.0
2023	0.0
Thereafter	2,670.6
Total	$ 2,670.6

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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