Reinsurance and Catastrophes - Effects of Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effects of reinsurance on premiums and benefits
Premiums written and contract deposits, Gross Amount	$ 1,255,557	$ 1,244,500	$ 1,280,903
Premiums written and contract deposits, Ceded to Other Companies	28,773	21,989	22,728
Premiums written and contract deposits, Assumed from Other Companies	8,259	4,606	4,324
Premiums written and contract deposits, Net Amount	1,235,043	1,227,117	1,262,499
Premiums and contract charges earned, Gross Amount	841,147	812,099	777,651
Premiums and contract charges earned, Ceded to Other Companies	28,837	22,036	22,826
Premiums and contract charges earned, Assumed from Other Companies	5,023	4,640	4,321
Premiums and contract charges earned, Net Amount	817,333	794,703	759,146
Benefits, claims and settlement expenses, Gross Amount	769,664	588,621	562,385
Benefits, claims and settlement expenses, Ceded to Other Companies	136,601	10,472	25,739
Benefits, claims and settlement expenses, Assumed from Other Companies	4,497	4,157	4,358
Benefits, claims and settlement expenses, Net Amount	$ 637,560	$ 582,306	$ 541,004