Investments in Fixed Maturity Securities (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items]
Held-to-maturity Securities, Restricted	$ 1,332,000,000
Insurance-related Assessments
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items]
Held-to-maturity Securities, Restricted	328,000,000
Reinsurance
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items]
Held-to-maturity Securities, Restricted	37,000,000
Letters of Credit Outstanding, Amount	3,000,000
523991 Trust, Fiduciary, and Custody Activities
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items]
Held-to-maturity Securities, Restricted	1,700,000,000
Residential mortgage-backed
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items]
Gross unrealized (losses) gains for debt securities	$ (55,090)	$ 76,467