Schedule II - Primerica, Inc. (Parent Only) - Condensed Statements of Cash Flow Parenthetical (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Fixed-maturity securities transferred	$ 35.5	$ 39.2	$ 12.9