Reinsurance - Summary of Reinsurance Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Gross Amount
Premiums written and contract deposits, Gross Amount	$ 288,816	$ 301,512
Premiums and contract charges earned, Gross Amount	207,737	200,455
Benefits, claims and settlement expenses, Gross Amount	151,968	147,271
Ceded to Other Companies
Premiums written and contract deposits, Ceded to Other Companies	5,514	5,510
Premiums and contract charges earned, Ceded to Other Companies	5,528	5,534
Benefits, claims and settlement expenses, Ceded to Other Companies	9,014	3,883
Assumed from Other Companies
Premiums written and contract deposits, Assumed from Other Companies	706	730
Premiums and contract charges earned, Assumed from Other Companies	789	801
Benefits, claims and settlement expenses, Assumed from Other Companies	608	708
Net Amount
Premiums written and contract deposits, Net Amount	284,008	296,732
Premiums and contract charges earned, Net Amount	202,998	195,722
Benefits, claims and settlement expenses, Net Amount	$ 143,562	$ 144,096