Investments (excluding Consolidated Investment Entities) - Impaired Loans (Details)	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans without allowances for losses	$ 4,000,000	$ 4,000,000
Less: Allowances for losses on impaired loans	0	0
Impaired loans, net	4,000,000	4,000,000
Unpaid principal balance of impaired loans	5,000,000	5,000,000
Mortgage loans in process of foreclosure	$ 0	0
Mortgage Loans, number of foreclosures	2
Mortgage Loans, Foreclosed carrying amount	$ 7,000,000
Greater than 60 days in arrears
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in arrears, amortized cost	$ 0	$ 0