Deferred Policy Acquisition Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of year	$ 198,151	$ 200,826	$ 201,762
Policy acquisition costs deferred	589,144	552,675	561,610
Amortization	(572,164)	(555,350)	(562,546)
Balance, end of year	$ 215,131	$ 198,151	$ 200,826