Investments - Amortized Cost and Fair Value of Available-for-sale Fixed-maturity Securities in Default (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Investments Debt And Equity Securities [Abstract]
Available-for-sale fixed-maturity securities in default, amortized cost	$ 5	$ 138
Available-for-sale fixed-maturity securities in default, fair value	$ 93	$ 262

Available for sale fixed maturity securities in default amortized cost.

No definition available.

Name:	pri_AvailableForSaleFixedMaturitySecuritiesInDefaultAmortizedCost
Namespace Prefix:	pri_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant